At the beginning, the trauma kyung so had wasnt as bad as the beginning. So he could have fallen for dong hyuk for real. After he finally left the yule and met dong hyuk, kyung so just couldn't stay with dong hyuk anymore because yule just always appear and remembered in his mind due to everything that happened at yule's house.
The cause of that was stockholm syndrome.
And because in kyung so's mind he always appear (and again due to all the traumatic things that had just happened) kyung so confused it with his love for yule.
The trauma / love aka stockholm was stronger than his love for dong hyuk thats why kyung so is pushing away dong hyuk.
Since kyung so came to think it was love, he wasn't able to endure the fact that yule will die when he stabbed himself. Since yule's existence has already been deeply engrave.
Kyung so won't be able to forget yule for the rest of his life and he is entirely become mentally all over for yule.
That's why the ending of Yule and kyung so ending up together, starting all over is the best for kyung so.
The another ending we all want kyung so not ending up with anyone or other than yule is a low key torture for kyung so because in everytime he'll have sex with someone he like like dong hyuk, he'll just keep remembering yule.
So I've been trying to analyse the characters the entire time, and honestly they do make sense but at the same time they need therapy cause there is no way they can be fine mentally or psychologically during or after this.
There are spoilers
First of all I understand why the sister wanted to keep the the uke by the semes side, to make him more 'human' but she didn't realise the mental stress that was causing the uke and the abuse he was suffering from both her brothers. She didn't know about their past, I get that, but it seemed like she already knew that he was being mistreated by the seme and tortured by her older brother as well. I honestly thought she was crazy at first for trying so hard to keep them together, but she is more ignorant about their relationship
Also I thought that the older brother might have had an Oedipus complex because of his mum, but it's more than that since he thinks his brother killed her, so I see why he tried to take the most precious thing away from. Obviously the seme didn't kill her but the brother doesn't know that, and he finds out either which is also why he tries to break them up. I'm not sure if his feelings for the uke are real or if he's just a sadist towards his brother, but he should have sent him to a mental hospital sooner...
The seme seemed a little crazy from the beginning but it was more like he was a child playing with his toys and instead of them breaking on their own, he wanted to break them first, and it started with his mother.
It's only at the end where his obsessiveness makes sense and why he wanted the uke to be fully dependant on him, since he couldn't even function properly without the uke. I was kind 9f hoping that for about 50 chapters he would have some sort of redemption arc or something since he definitely had a lot of redeeming to do. Also he is more manipulative than I gave him credit for, he practically played both his brother and the uke like marionette dolls.
The other guy suffered as well since he has been trying save the uke the entire time but the uke always went back to his ex. He probably felt helpless or even useless to the uke and thought the only way out would be for one of them to die. But obviously he wouldn't want the uke to die, he was putting on a 'show' to make it seem like he was actually going to kill him so that seme would feel worse at the moment.
I felt so bad for the uke the entire time. First he suffered from trauma from something that happened 3 years ago, and when he thought he could be happy he was basically kidnapped by the seme. Even though he wanted to leave the sister tried everything she could to keep him in that house, and same went for the seme. It was the older brother who told him to leave and continued sexually abuse him because he didnt, which made it worse because he did want to but he was practically locked inside a cage. Essentially the only person he could rely on was the seme and even after going back to his other boyfriend the impact the seme had on him didn't leave since he would always say that he would go back to the seme to protect the person who was there for him. He didn't really have choices that would end well for him since either way he would suffer at the end. Either go back to your abusive boyfriend so that your other boyfriend doesn't suffer, or stay with your other boyfriend and watch him suffer instead.
Anyway I was kind of hoping that the uke would end up with no one since I feel like that would have been better for everyone. But since he ended up with the seme I was hoping that in the epilogue they could have sorted out their relationship and they would have made some effort. Right now it seems like they are back where they started after they reunited when I was hoping their relationship would at least be close to the relationship they had when they just started dating.
The seme should have taken more interest in the uke since even at the end he still doesn't know anything about him, like his favourite food. Instead of trapping and stalking him all the time he should have tried to be on good terms by starting their relationship again to before they were lovers, or even friends so that they can slowly build their relationship up again without him forcing his opinions and desires on to him.
Sorry this is so long, I didn't even write everything I wanted to say.