He doesn't deserve it. Nobody deserves it. Your logic is really flawed if you contemplate for a moment. I'm not defending Kwon Jiwook's past actions, but he forgot everything about the past, and what Park Juyeon did was truly horrendous, torturing Kwon Jiwook without even explaining why he's doing it in the first place. Kwon Jiwook is decimated at the end to the point where he can't even utter a word of defiance to Park Juyeon, and is trapped in that toxic relationship forever.
And, how about the other men that were involved in the raping of Park Juyeon? They have no karma or anything. And, how about the men who raped Kwon Jiwook? Aren't they rapists either? Did they face any consequences? I bet they didn't.
He should have just killed Kwon Jiwook, but Park Juyeon is so obsessed with Kwon Jiwook that he chooses to be the perpetrator in the guise of revenge.
Spoiler!!!
Park Juyeon(top) is doing this because Kwon Jiwook(bottom) constructed a gang rape when they were in middle school and filmed it and showed it to his mother, leading to his mother being hospitalized due to severe mental shock.
Now, the Manhwa is in chapter 18(before the first gang rape Kwon Jiwook would suffer from). Basically, after he ignored Park Juyeon's impellent, Park Juyeon made other men gang rape Kwon Jiwook and then kinda kidnapped him and trapped him in his house. He treated Kwon Jiwook like a sex slave, a pet dog, and he didn't let him leave that room for months. (Kwon Jiwook was tortured every day as well)
Kwon Jiwook later tried to leave and Park Juyeon caught him once again. Another gang rape just like that but this time was so detrimental that Kwon Jiwook was hospitalized and became so mentally unstable. He tried to kill himself multiple times after that. However, they do end up together because Park Juyeon is still obsessed with Kwon Jiwook and Kwon Jiwook even begs Park Juyeon to stay with him because he's so petrified that those men who raped him would find him again, believing Park Juyeon is the only person who can keep him safe despite Park Juyeon being the culprit of the whole thing.
This story is truly fucked up, so let this be a warning whether you want to continue reading this.
I mean it's true that Jiwook lost his memory and Juyeon didn't tell him what he did ,but he still had his narcissistic personality. Ik jiwook as well is a victim, but it can be said that his past actions lead him to his state. And unlike othere manhwas or managas where the victim didn't deserve the torture (like non zero sum ,bad life or barge in ) here Jiwook def did really bad and had to face his consequences.

Ok o lemme get this off my chest right away. This is my opinion so NO ONE IS CANCELING ME . I just finished reading the novel and oh my lord . At first I was super mad at the top (park juyeon) for being so batshit crazy and like idk psychotic towards Jiwook I felt bad . But then their flashbacks came and lemme tell u something , whatever the "torture" Jiwook had to face he deserved it . When reading the novel my thoughts where Like boy the things that 14 year old(the top) had to face is just so sad and devastating and that to by the person that they loved NAH HELL NAH. The things he had to go through and even in the side stories that shows the past ,be was still such a pookie(obvi the top). Look u might trash the top,but he had all the right to vent his anger toward the man that destroyed his life. KARMA IS A FUCKING BITCH . And I want all the rapist in this world to face the same humiliation and horror that their victims had faced 10×.