Okay here it is:
MC doesn't think he has long to live due to his addiction to the inhibitor that's breaking down his body and he has given up on waiting for ML
ML also return after 13 years, and he is now 27. ML usurped redhead (Marstiel) and became the new guardian of Blue Warren. He also discontinued MC's inhibitor supply after taking charge, causing MC to stressed out and went to look for redhead, only to discovered that ML is now the new guardian. When they met, ML audaciously demand that MC fulfill their earlier marriage promise. MC refused, feeling sad and betrayed. ML then attempted to assault MC after being refused, and after stripping MC he discovered MC's cracked and bleeding fingernails—clear signs of his long-term inhibitor use. ML expressed shock, stating, "I didn’t think you’d be taking the inhibitor for so long!" (ಠ_ಠ) This pisses me off even more because it shows a complete lack of understanding and consideration for how MC managed his heat and unwanted imprint during ML's absence, especially when ML had even requested MC to avoid other alphas before he left. ML offered no apology; instead, MC learned through his chamberlain that ML felt "very regretful" about his prolonged absence and its resultant effects on MC, wishing he could have returned sooner. (╯'□')╯︵ ┻━┻
After MC rejected him, ML continues forcing himself on MC (consent was dubious), threatening to kill Redhead, and threatening MC's kingdom's income (salt supply), etc. until MC agreed to marry him.
The reason ML disappeared for 12 years turns out to be a result of a stupid misunderstanding. One evening, while MC was experiencing his heat, the regent snuck into his room like a creep with the intent to assault him. During this incident, the regent began rambling nonsense—unfortunately, I cannot recall the specifics. However, Aleph, who was eavesdropping at the time, overheard this and misunderstood. He mistakenly informed ML that MC was responsible for the death of his parents. I cannot get over how Aleph was just there eavesdropping while MC was about to be assaulted instead of doing something to help. Anyway, rather than feeling outraged, MC found it...touching (????) that ML still wants to marry him despite believing that he had killed his parents. However, it turns out ML never believed Aleph's accusation that MC had a hand in his parents' death. His reason for leaving was due to another stupid misunderstanding: he found an unsent letter in MC's study, addressed to "Marstiel"—a name that belonged to ML in the previous timeline but is now Redhead's name, but MC still had trouble adapting to the name change in the second timeline so sometimes he would mistakenly address ML by that name. This caused ML to believe that MC has feelings for Redhead. So out of jealousy, he left and when he returned, he took over Redhead's guardian position as well as the name "Marstiel"—because "Marstiel" is who MC love. (ಠ_ಠ)
Anyway, they resolved the misunderstanding and got back together. In the epilogue, ML recalled fragments of the past timeline through a dream, including the moment of MC's death. When MC shared details about their previous experiences from the past timeline, ML realized that his dreams were memories of that past, which caused him to cry. Fortunately, this version of ML acknowledged that MC was never responsible for his parents' deaths in either timeline and recognized that MC was also a victim. Ultimately, they imprinted on each other, got married, and MC overcame his inhibitor addiction, resulting in a happy ending.
FATE OF THE REGENT:
If you're curious about what became of the regent, that part is actually very satisfying. When he snuck into MC's room, MC defended himself effectively and managed to capture the regent. MC's chamberlain heard the commotion and ran into the room, grabbed the nearest wine bottle, and smashed it onto regent's head the moment he saw what was happening to MC. I love MC's chamberlain so much, he's only other character I like besides MC and maybe Redhead. Since then, the regent has been imprisoned for 12 years, enduring severe tortured: he was chained up, lost an eye, became crippled, and had his tongue removed. Also, a section of skin on the back of his neck was sliced off, causing him pain whenever he tries to release his pheromones, so MC no longer fears him. MC even visits him occasionally to gloat. Most people believe the regent simply returned to his territory and became reclusive. Oh, the regent also retains some memories from the past timeline, adding to his misery. Good riddance, truly a fitting outcome for such a detestable character. I get the biggest ick whenever he appears.
MORE RANTS FROM Sher0n
This story was really frustrating for me to read. The MC is undoubtedly the biggest victim, yet hardly anyone in the narrative seems to fully recognize how miserable and degrading his life has been (especially in the first timeline), enduring 13 years of assault and manipulation by the disgusting regent that forced the imprint on him during his most vulnerable moment. Only his chamberlain in the second timeline seems to truly understand, breaking down in tears when MC decided to be honest with him. It's baffling how little shock or compassion others show.
The whole story was just full of miscommunication, misunderstanding, and ML threatening MC to get what he wants. When an MC has lived such a miserable life, I wish for him to find an ML who is gentle, caring, and genuinely prioritizes his wellbeing. If the ML is less than kind, he must at least show significant remorse, grovels, and make amends for at least half the amount to MC's suffering to make their relationship acceptable in my eyes. In the first timeline, MC died before ML could apologize or recognize his mistakes. In the second timeline, ML remains domineering, using threats to get his way despite having no right to be demanding after disappearing for so long. The audacity (╯'□')╯︵ ┻━┻. I guess he did eventually showed remorse, but this whole situation made me feel as though MC had escaped from one manipulative alpha only to fall into the clutches of another. Absolutely tragic. I need the love of MC's life to at least match the level of care MC's chamberlain has for him
Sorry a bit of the first part got cut:
2ND TIMELINE / REGRESSION:
Even in this second timeline, the ML remains problematic. The MC did not imprint on ML and successfully prevented the exile of ML’s parents in this timeline. However, they still died in an accident while relocating to evade the regent until MC become of age to legitimately inherit the throne. ML and MC agreed to reunite after MC turned 19 and ascended to the throne. MC unfortunately did not regress far enough to avoid being imprinted by the repulsive regent. So, MC plans to avoid exposure to the regent’s pheromones, aiming to prevent the dependency and significant impact it had on him in the previous timeline.
As part of his plan, MC hired "redhead" (what he called ML's 1st timeline assistant). Redhead is now named "Marstiel" (weird MTL lol) instead of ML due to MC altering destinies. MC wants Redhead to create an inhibitor for him (the opium). MC planned to use this inhibitor for three years while waiting for ML’s return, despite the known risks of dependency and addiction associated with prolonged use. (Basically, MC decided to take inhibitors while waiting for ML to become of age, and they can figure out what to do about regent's imprint on MC after ML return). This is where it gets infuriating...ML did not return after three years but instead went missing for 13 years.
After a timeskip, MC is now 29 and is looking to get married to he can leave a descendant. This is because MC doesn't think he has long to live due to his addiction to the inhibitor that's breaking down his body and he has given up on waiting for ML

Damn I was suuuper hooked on this, especially with the cliffhanger after the most recent chapter. But after reading the spoilers I'm considering dropping this. Wow was that disappointing to read. I really wanted to ml to be a better person since he wasn't fueled by revenge and hate for the imprint. Super bummed that he turned into a manipulative asshole once again...