
Such a huge mess... Nobody is at fault in this situation, everything is so complicated, all I can do is wish for everyone's happiness..

What do you mean no one is at fault? Just because it got complicated doesn't mean that there isn't a clear right and wrong here. Youngwoo let Taejoo believed he raped him so they could be in relationship since he was in love with him. That is clear fault, because the minute Taejoo said that, he could have cleared it up, but out of selfishness he didn't. Taejoo tried to take responsibility by being with him. Imagine you have a friend that has been there with you as you were suffering, then one day you woke up with them next to you believing you forced themselves on you and you feel such guilt that you put your desires to the side and prioritize that. To the point that when the person you actually loved comes back and wants to be with you, you bitch slap them and tell them to never call you again. Just because you have a one sided crush for a long time doesn't mean you aren't still at fault for forcing yourself on them when they are drunk, making them believe it was their fault, guilting them into a relationship, making them cut ties with the person you know they really love, and then suddenly being mad that they didn't love you back while knowing that the reason they were with you in the first place was out of guilt, responsibility and wanting to make you happy at their own expense. How is no one at fault?

That it's in fact wrong, I've read till chapter 48, and sadly taejoo also admits he take advantage of this kid, cause he never loved him and just wanted something to "forget" our mc, so he's not a saint either, and when he founds out about it (that he never raped this kid) he feels like their are in same ground now since both did terrible things.

I'm not saying he is a saint, all you named was another fault in the situation, that is a far cry from nobody is at fault. It just means that Taejoo also used youngwoo and felt guilty about it, but that is not comparable to what youngwoo did in the least. If you cannot tell the difference, then I don't know what to say to you. They both suck, but youngwoo sucks way way more.
Mr Kim is such a turn on, so manly and dedicated to seunghyun (づ ̄ ³ ̄)づ