
A more detailed SPOILER below if you guys want to know more about Lucio and Rose's relationship and how the relationship between Rizi and Lucio develops. But this is simply MY interpretation because.....
I see Lucio as a broken person. He can't love in a normal way. Which was why Rose was able to take advantage of him so easily, and eventually how Rizi was able to redirect Lucio's feelings from Rose to herself. The easy redirection later becomes one of Rizi's insecurity on the sincerity of Lucio's feelings.
Anyway, back tracking. The previous Queen is infertile. So the the previous Emperor had a child with one of his maid and thus Lucio was born. The Queen was driven to insanity by the fact she can't have a child and that her power was stripped away by a mere maid. So in one of her bouts of insanity, she stole the child from the maid and tried to raise the babe as her own. The emperor is pretty indifferent about the affairs of the inner palace, and so allowed it. He couldn't really reprimand the Queen either as she's from a powerful Duke Owsin house. At first the Queen was kind to Lucio, and so Lucio grew up thinking the Queen was really his mother. But then the Marquess Ephiney house started to scheme against the Queen, hoping to depose her in order to strip power away from house Oswin. They used her insanity and jealousy to make her resent the maid that stole the Emperor's love and hate the child she ended up birthing. This is when the Queen started to abuse Lucio. She would beat him black and blue, sometimes to the point where he think he might die. She would mentally and emotionally abuse him, call him dirty child, child of a whore, etc. She'd lock him up and starve him. Her abuse would lessen when the Emperor was in the palace, but the Emperor was often on expeditions, conquering neighboring countries, so there were long spans of time where the Queen could abuse Lucio with no one able to stop her. Since the Queen isolated Lucio from everyone, Lucio craved love and he tried to get it from her since she's his mother. He would try everything to please her, so when she beat him, he thought it was because it was his fault. It was his fault that he did something wrong to make her displeased. Then on his 15th birthday, the Queen invited Lucio to her palace (which is the current Queen's palace that Rizi lives in). Lucio still had hope that the Queen loved him and was happy she said she had a birthday present for him. Lucio was so delighted, thinking that this year might be different since she remembered his birthday and was giving him his first birthday present ever. (The palace never celebrated his birthday, although he's the crowned prince). She points to a figure tied to a chair with a white blanket covering them. The Queen says that's his present, and Lucio is like what do you mean? The Queen orders him to kill that person. Lucio, shocked, refuses. He doesn't want to kill someone. He begs her to not make him. The Queen takes a cane and beats him. She beats him so bad, he ends up fracturing a leg and breaking an arm (I think). He's bleeding all over the place and the pain got so bad, he started feeling numb. His mind goes hazy and he thinks he might actually die this time. So when she asks him will he kill the person or not, or does he want another beating, Lucio cries and begs her not to beat him anymore, he'll do it. He'll kill the person. Lucio ends up stabbing the person under the blanket several times, feeling nauseated from the blood and almost throws up from the feeling. After he's done, he falls to his knees, panting. The Queen is behind him, laughing. She congratulates him for becoming a murderer and tells him she's not his real mother. Hearing that, Lucio is relieved.....he's glad she's not his mother because how could a mother hate her own child? Then she reveals his REAL mother is the one he just killed. Lucio breaks. He tears off the blanket to look at his mother's face and touches her, the warmth of her body slowly dissipating in the rain. Lucio falls to the ground and screams and screams in agonizing pain at killing his own mother. And this is when Lucio psyche is truly broken. He thinks himself a monster, a murderer, someone that no one can love. He has nightly nightmares about the Queen's abuse, panic attacks if he sees sage (the Queen's favorite flower was sage flowers, and she's used to drag him to her garden to beat him), and his psychotic episodes are when he dreams of his real mother. In his psychotic episodes, he would be lost in his own world and scream until he tears his own voice muscle. He would also inflict pain on himself. Lucio thinks he deserves these nightmares though. It's God's punishment because he's a monster that murdered his own mother.
As for the Queen, once the Emperor came back from his expedition and found out, she was deposed. The Oswin house fell into ruin and the Ephriney house that orchestrated this rose from a Marquess to a Dukedom. Rose found out about this through January. January is accomplice of Rose and the concubine of Duke Ephriney. Rose blackmails Duke Ephriney with his treachery and says if he doesn't want Lucio to find out and wipe out the entire house of Ephriney, he will help her become queen. So through Ephriney, Rose "coincidentally" met Lucio despite being a lowly baron daughter. Through her charm and arts of seduction, Lucio fell for her. What Rose was good at was finding people's weakness and desires. Through their weakness, she blackmails or coerces them. Through their desires, she manipulates them. So knowing Lucio's trauma, Rose acts gentle and innocent in front of him. On his nights where he's having an episode, she pretends to be sympathetic and understanding. She takes Lucio in her arms and pets him, telling him toxic and gaslighting him with words such as, "My poor majesty. You're monster that no one loves. But I'm here for you. I'm the only one that will love you. I'm the only one who understands. You have no one else but me." While it's true that Lucio severely depends on Rose, that's not the only reason why he won't leave her. In order to tie Lucio even more to her, she tells him she's the only one who understands him because she also suffered abuse of her own.
Rose is also a pretty sad person. She is the daughter between a prostitute and Baron Darrow. When Rose was ten, she was rescued from the brothel by Baron Darrow and formally adopted into the house. However, rather than the daughter of the house, she was treated more like a maid. Then as she got older, she got the attention of her older half brother...........her brother repeatedly raped her while she lived in that house. Though the Baron and the Baroness knew what was happening, they turned a blind eye since if this was made public, it would be an embarrassment. And so that's why Rose is obsessed with power. She never wants to be looked down on or helpless ever again. Lucio is sympathetic to her. He knows how it is to be helpless, and so since he "loves her" and because she's the "only one that understands and helped him", he agrees to make her Queen, the highest position a woman can take in the empire. (In the side story where Rose becomes queen, Rose still isn't happy. No amount of jewel or riches was enough for her. She still felt empty. She often lashed out and got angry at people, accusing them of looking down on her despite being queen. So in truth, Rose thought being queen was enough to make her happy, but she was wrong).
So in short, Lucio and Rose /may/ have loved each other in the beginning, but in the past year they've been together, it dwindled down to Lucio feeling pity and obligation for Rose, but since he never experienced or knew what love was, he confused his feelings of pity for love. On Rose's end, she did love Lucio, but she loved his position as Emperor more. She loved the power and money his position gave her. Once Lucio stopped favoring her, she started to use his trauma and weakness against him in order to drive a wedge between Lucio and Rizi.
For Lucio and Rizi's relationship. The turning point to the relationship is after the Hunting Competition. Side note, Lucio and Rose's relationship start to sour after the Envoy Dinner. Lucio got to see a crack in Rose's facade, that she isn't as understanding or as sweet as he thought. Rose sends assassins after Rizi and Lucio ends up taking a poisoned arrow for Rizi. Lucio faints from the poison and Rizi becomes Queen Regent and puts Rose in jail while they investigate the case. Anyway, right around here, Lucio starts to waver between Rose and Rizi. He isn't in love with Rizi. It's more like he feels guilt and pity to her. He put her in this position in order to promote Rose, meanwhile, Rose is turning into a treacherous person....Rizi bumps into Lucio at the garden again and asks Lucio does he love Rose? And Lucio's inner monologue says usually he would immediately answer yes, but now he hesitates. Lucio finally answers and says he doesn't know... Around her, Lucio begins to realize what he feels for Rose isn't love. It may have been love, but now, it's more like he feels sorry for her. So he asks Rizi can she just spare Rose if she's convicted? Rizi can do anything - strip her of her title, exile her, even fake her death so that Rose becomes an invisible person with no status or name. But please, just don't kill her. Rizi refuses. Rose tried to kill royalty and Lucio even got injured and almost died. Rose can't escape the ultimate sentence. Lucio purses his lips, but doesn't argue. However, there isn't conclusive evidence, and with Duke Ephriney interfering, the case was closed without anything being resolved.
Okay, but afterwards, a couple of things happened between Lucio and Rizi. Rizi finds Lucio in the rain and Lucio ends up telling Rizi about his past. He tells her the entire story in a robotic, nonchalant type of way. Which breaks Rizi's heart. She cries for him and he wonders why she's crying? She tells him because she feels sorry for him. What he experienced, no one should ever go through. His life was sad and pitiful, so he should cry. Not only cry, but yell and scream at the injustice. Lucio realizes this is the first time cried on his behalf and told him it was okay for him to cry as well. I can't really remember, but Lucio and Rizi both end up hugging each other as they cried. Rizi woke up with swollen eyes lol. Also, Rizi wishes she never heard Lucio's story because now she feels sorry for him. She never wanted to feel anything for Lucio. She only wanted to see him as an emotionless and heartless ruler. Not someone with feelings. But now that she knows his tragic past, she feels sympathy for him. Lucio also begins to notice Rizi, and he appreciates that her feelings for him didn't change. Rizi tells him to his face that she still hates him, to which Lucio smiles and says okay. He tells her that usually when people find out about his story, they start to avoid him or treat him like he's fragile. So he likes that Rizi is still the same. It makes him feel a bit more normal. Another incident that happens is that Rizi also finds Lucio during one of his psychotic breakdowns. She was able to snap him out of hurting himself. While Lucio isn't quite lucid, Rizi tells him he needs to stop...He needs to stop making her feel sorry for him. She just wants to purely hate him, and she can't do that if he keeps showing her his pitiful and vulnerable side. Just as she gets up to leave, he holds onto the hem of her nightgown and begs her not to go. Rizi sighs and says, "It's not that you don't want me to go, it's that you don't want to be alone." Lucio looks at her with teary eyes but stays silent, because what she says is true. But Rizi is so tired, that she's like whatever and ends up falling asleep with Lucio holding onto her like a scared child.
Lucio begins to seek Rizi out like a child or puppy seeking love. I know in the beginning of the manhwa/novel, Lucio seems like a BIG JERK with capital letters, but after Rizi makes her ultimatum and threatens him about her being the one to give birth to a crowned prince, Lucio never does anything disrespectful to Rizi and tries to protect her in his own way. Rizi begins to notice that Lucio is VERY attentive to her. At banquets or when she's walking alone, Lucio would be the first one to find her. He'd ask in a worried tone where are her guards? He'd also take off his coat and put it around her since she looked cold. Lucio also would try to talk to her and continue the conversation despite Rizi cutting him off or acting cold. Rizi doesn't want to be moved by Lucio's kindness. She is basically fighting for her throne and the life of her family, so she can't risk wavering. But Lucio's consideration is putting a crack in the wall Rizi built for herself. During National Founding day banquet, Rizi finally confronts him and asks him why is he doing all this? Lucio says it's because he's doing his husband's duty. He should look after his wife's wellbeing. Rizi laughs sarcastically and calls him out on his bullshit. She says a husband's duty is being faithful to his wife and doing everything he for their relationship. And since he can't do either, he should stop while he's ahead. Before Rizi can walk off, Lucio whispers what if he can fulfill both? What if he could remain faithful to her and try at their relationship? Rizi laughs again and mocks him. He failed both since the first night of their wedding. Rizi says if he had done it from the beginning, Rizi would've tried as well, but since he couldn't keep his vows, there's no turning back time. A broken vow is a broken vow, so stop trying to pretend to be her husband, it's burdensome.
A couple of things happen and Rizi finds out the reason why she was chosen as Queen was because she's barren. Her relationship with Lucio completely breaks down here. Whatever sympathy or feelings she felt for him is gone. She tells him she hates and despises him. She regrets ever feeling sorry for him.
Anyway, the short story of Lucio's feeling to Rizi is more like he transferred his dependency from Rose to her. When Rizi tries to leave the palace, Lucio begs her not to go. He gets on his knees and says he can't live without her, that he has no one but her now. He'll do anything she wants, give her anything she wants, but she can't leave the palace. That is soooooo not healthy. Btw, that scene is less like a possessive creepy monologue, but more like a sad child begging his mom not to leave him. Majority of Lucio's feelings to Rizi is more or less like that. And that's why Rizi is so reluctant to be in love with Lucio. She fears so long as someone is nice to Lucio and comforts him, he'll transfer his feelings. He did so with Rose and fell in love with Rizi so easily. Rizi is afraid he'll fall out of love with her too, and then she'll be the next one to die. Lucio tells her he loves her, and Rizi rejects him hard. She draws a very clear line between them. She does NOT want to be in love with him. But Lucio, once he "loves" someone, he loves with all his heart, and he tells her she's different from Rose... Rose hurt people to gain power, and her beheading was her own doing.
Side note: while Nilla was framed for treason, Nilla DID do some shady things to try and win Lucio's love. Nilla said she hated the person she became to win the love of Lucio, she became mean and petty and did atrocious things in order to gain his attention. In the timeline where Nilla was queen, she ALSO found out about Lucio's past. Nilla also had the chance to take Lucio's love, but she couldn't handle Lucio's trauma. Nilla admits that she didn't have the fortitude or patience that Rizi did. She abandoned any chances to be with Lucio because she just couldn't handle the emotional burden at being with someone so broken.
In the end, Rizi finds Lucio again during one of his psychotic breakdowns. As she comforts him, she finally caves. Her inner monologue is something like I don't know where my pity ends and love begins. I don't know if this is love at all. She thinks she's too kind and softhearted, and that her softheartedness got her caught up with Lucio. It's more like Rizi was tired of her anger and resentment. Lucio is pretty sweet to her in the last few chapters, so Rizi decided to "fuck it", sure why not. Let's just try.
So the reason I enjoyed it despite how messed up their relationship is, is because it's not a "love cures all" type of story. Lucio is still very broken - he just changed the person he depended on. Rizi also never fully fall in love with Lucio. She's not even sure if what she feels for him is love or pity, or a mix of both.
If you've gotten this far, kudos to you lol. Thanks for coming to my Ted Talk

It still has a really happy ending and the side story goes over Rizi's infertility issue. But I can't go into detail about that because that side story hasn't been translated so I have no idea what actually happens. I just know that side story exists.
A lot of people in the forum aren't happy with the ending or think the love story is too rushed, or that Lucio is a very weak male lead. I was pretty okay with the ending because stayed a very strong female character. HER happiness never depended on being with Lucio. And while their relationship isn't a traditional lovey-dovey type, it has the makings of one because both of them are working hard to make their relationship work. So the story ends with the two of them pretty content. Like some people think their romance is weak, but if you view it under a different light, their love is just different.

Np! I did skip a lot of key scenes though (bc it would've been even longer otherwise lol). I would stick around for the politics and if you liked my interpretation of Lucio/rizi's relationship, there are a lot of scenes where their relationship is explored that I didnt have time to write. But I will say, other than the end, they don't have too many sweet scenes together. If you want an ML groveling for love, then this is it.
So I just binged read the novel. If you want to start the novel. Ch 25 from the manhua is around chapter 28-30ish in the novel.
SPOILER. (But still keeping it a tiny vague)
they do explain why the emperor is so attached to Rose. Basically, it's not out of love. Both of them a very scarred people with very traumatic pasts, so they're staying together to lick each others wounds. Rose found out Lucio's childhood trauma (which is only a few higher up nobles are supposed to know) and took advantage of it. She made Lucio dependent on her. While Lucio is a competent king that can handle political and financial affairs, because of his abuse, he's very frail emotionally. You'll see later in the manhwa - he has nightly night terrors, psychotic breakdowns, and anxiety attacks.
Lucio starts to fall for Rizi when he finally reveals to her the secret about his past and she cried for him. Rizi was kind and pitied him, and she didn't victim blame him either.
And the story does a good job explaining that Rizi might not even truly love Lucio. What she feels for him is more akin to pity and sympathy, and Lucio might not even truly love her. But he got attached to her like he did Rose because Rizi didn't spurn him when she learned about his past and also comforted him during one of his breakdowns. And honestly, that's really how it felt in the beginning of their relationship. Lucio felt like a kicked puppy trailing after any crumbs of affection from Rizi. But because Rizi is a healthy, normal person, she slowly guided Lucio to a REAL healthy relationship. By the end of the main story, both of them are quite lovey dovey.
The first side story covers when Nilla was deposed and Rose was made queen. So it meant Lucio stayed with Rose in that alternate timeline. After Rizi and her family got beheaded, Lucio became more unstable from the guilt.His relationship with Rose also became strained.
Side note: other than the wedding night, Lucio never actively took Rose's side. At least from what I noticed in the novel. He either remained neutral (when he thought he still loved Rose) and so didn't punish Rose (but also didn't negate Rizi's valid points. Or he actually took Rizi's side when he knows Rizi is right. Never noticed him ever taking Rose's side.