
For those of you who don't get it , Blondina is blind to Amon's feelings for her not because she is "dumb" but because she lacks the confidence to believe she is worthy of being loved in that way. Trauma can do that
to a person.
She has been conditioned to believe that she is a lowly person whom isn't loved by anyone. And should not expect it from others.
Because of the Emperor abandoning her and her mother to seek greater pastures. The emotional and physical abuse she endured as a child. And even when she became a "princess" she was treated as Inferior compared to her siblings by most people around her.
The first instructions she gets from her father upon their "reunion" and entering the Palace is to basically keep her head down and not cause him problems.
He exiled her to a separate palace to keep her out of the public eye because he was ashamed of having a "mixed" daughter.
Meanwhile , having to watch him dote on his other kids (especially Adellai) like a real father.
Also, her father never bothered to give her the same level of education as the twins got and she was always left with with scraps.
Not bothering to teach her the ancient tongue that can only taught orally and is meant to he known by all royals and giving her thoughtless gifts. For example presenting her with a blue dress to wear at a Royal banquet despite there being a dress code for the event which meant she was humiliated.
The hunting contest where all the hunters purposely ignore her in favor of her sister is a perfect example of this poor treatment and discrimination she gets compared to her siblings.
It's why that repulsive Phillip targets her because he wants to be the "savior" of the pitiful princess that (he thinks) no one wants due to her being "inferior".
And in his warped mind he believes Blondina will be grateful to have someone of his (he sees himself as above her) status to even take notice of her.
The only person who treats her with respect and doesn't look down on her in the Palace is Lucy.

I blame the Emperor... she is clearly his favorite child who takes the most after him in her ruthless ambition. And disregard for others. Both her and Emperor have little affinity for meaningful relationships with others unless there is a benefit for them. This is demonstrated by how Adellai uses those around her and how she tries to manipulate her brother when possible. Also by how she mistreats her own sister for being "inferior" and a potential rival for her current spot as the favorite child.
The Emperor is of a similar nature by how he used and deceived his lover (Blondina's mother), because she had blond hair and golden eyes (believed to mean you are descended from the one who can control the divine beasts) but since she had no powers as he hoped, he left her to seek the throne and power. He blatantly lied to her that he would "return" which she still believed even while she suffered in hardship and poverty waiting for him and as she laid on her death bed.
Meanwhile, he had taken the throne and acquired himself a high-status aristocratic wife, and started a new family. Neglecting the one he had already created to live like dirt. The only reason he "claims" Blondina years later as his child is due to a relic of his that she had being discovered after it got pawned and in fear she could be used by his enemies as leverage. Not due to fatherly sentiment.
For all his flaws. Lart is different.
As we can see from Lart's feelings for Lucy and his desire to "woo" her not as a lover but his wife despite her status as a "fallen noble" shows he is different from his father who used and abandoned his lover for the throne. And ditched her because in his eyes she wasn't "worthy" enough to be his wife or future empress due to not having powers to control shinsu as he had hoped and her being a "commoner".
Whereas, Lart wants the throne to protect and uplift the one he loves. For the Emperor power and status took precedent over his commoner "lover" and responsibility to his child both of whom he abandoned. Even Lart asks his father how he could have done that?
Since to Lart, his Love for Lucy means more to him than the throne. He is only pursuing it because it means he can protect her and raise her family's status if she were to marry him. And he doesn't care what people think or say about his choice of bride. The heart wants what it wants.
The Emperor is such a bastard he is purposely pitting the twins against each other in hopes they will both do his bidding in pursuit of the throne.

She got more closure and a better explanation to his past relationship from the ML's slutty borderline rapey ex than the ML himself.
I still don't get why he "brushed" her hand the moment he saw the ex-girlfriend? Based on what the ex said the ML chose to date her out of feeling "responsible" for her.

It means that most likely the manga was dropped by the publisher and the artist was told to wrap things up. Which is something very common in Japanese manga - especially josei/smut/shoujo.
It's why a lot of the stories also drag on longer than they need to with 80+ or 100+ chapters because the artist had been asked or encouraged by the publisher to continue the comic until informed otherwise.

Who are they kidding?
I don't think he bats for the team where procreation is possible unless its an omegaverse lol. The "candidate" looks and dresses like a slutty uke from a fantasy Yaoi smut.
Something tells me he wasn't servicing female clients at the brothel where he worked.

Wow. I thought he was more like a Loli-bait boy. But it's not unusual for boys to be dressed as girls until the reach of a certain age. A lot of cultures believe that it builds character in the boys. In the US even one of the president's was dressed as girl when he was child. In some parts of the Japanese culture and in a lot of Korean culture it's still practiced. But if he looks like a you slut that may have more to do with that face of his rather than his dress. That face just screams femboi, or uke.
Its very realistic given the circumstances to how their "relationship" started. It was mainly lust that brought them together and although they did start to like each other - they lack the emotional compatibility to make it work as a proper couple even if their "sexual compatibility" is amazing that alone isn't enough to build a foundation for a longstanding relationship.
I mean he sees her with another guy in the street. His first response? Go on a date and fuck the first doe-eyed thot battering her eyelashes at him. Talk about lack of restraint.
It's good that in this case, the decent 2ndML this time got the girl.
I think this has mainly to do with the FL's personality above all she has always been a practical person. She made a wise choice.
I think the title itself "match made in bed" considering this is a josei genre (although smut) was a foreshadowing clue that is far as their relationship will ever go.
The ML has more maturing to do.