The way things are going, Sangwoo is probably going to misinterpret Bum's intentions and end up either killing him or hurting him really badly because of his trauma with his mom.
Everything Bum does in the story is paralleled with Sangwoo's mom's own actions so I can see Sangwoo thinking Bum is trying to kill him with the rat poison and even cheating on him with the one girl (much like his mom cheated on his dad).
If he does end up hurting/killing Bum though, he will probably find the gift he bought for them afterwards and feel guilty for everything. These two need a lot of mental help tbh Dude hallucinating at this point. It's only a matter of time before things go wrong one way or another.
How come i see you post on every popular yaoi forum lmao
This chapter basically completes the reasoning for why Sangwoo constantly went around killing women. He associated them to his mother's memory and tried to recreate all the events between himself and his mother but this time putting HIMSELF in a position of power. It was his way of coping with his trauma caused by years of physical and emotional abuse from his mother where she was in control of his life. He just didn't know what to feel for her since he loved her when she was kind but hated her for everything she did to him. It's pretty sad tbh :/
All this time he just needed serious psychological help so he could learn to deal with his issues in a healthy way but his mother made him ALWAYS feel guilty for what happened to him. Always made everything that went wrong his fault to the point that he believed it and never seeked outside help. Instead, he blocked out the fact that he was ra*ed by his mom (as shown by his conversation with Bum when Bum told him about being ra*ed by his uncle) and tried to put on a facade of being the same person he was before (a popular, handsome guy who is kind and gets along with everyone) while taking all his issues out on innocent women.
It's truly interesting to see how all these points come together and how much detail went into every action Sangwoo has done since chapter 1.
I'm sure he didn't blocked the memory of his rape because he accused Bum to be a disgusting slut because he didn't react and didn't stab the uncle. While he immediately stopped the mother punching her and taking the knife, even though in the end she killed himself.
I don't even think he blame himself, since we have seen when he killed the ski resort woman that he says " why do you made me do such things?" He knows is his mother's fault ( and it is) with the murders he feels in power and takes revenge on her.