
Spoilers
.
.
.
.
.
.
Well, at first it looked like at least Bum was happy in his fantasy world. He told Sangwoo that he enjoyed the sex but once Sangwoo left the room he started to cry :/.
On top of that Bum didn't do anything without Sangwoo's permission. He didn't even enter the kitchen until Sangwoo indirectly told him to.

.
.
.
.
.
.
.
He dreams about playing soccer as a child. He sees his mum kneeling on the ground but ignores her. We then see him as an adult/teenager resting his head on her lap but something happens (maybe she said something? it's not shown what exactly it was) and he gets angry and walks away. However, he can't do it because there's a wall in front of him. He picks up a knife that is lying on the ground and walks back to his mum but then she suddenly turns into Bum. Bum gets closer to him, Sangwoo falls on his knees, Bum hugs him (with a lot of strength behind it) and asks "Is mom disgusting".
He wakes up, talks with Bum and seems to be a little bit angry at him but then he sees Bum's face from the dream again, apologizes and walks away. That's when Bum cried.

Spoiler
I think I'm kind of understand a little about Sangwoo's trauma now. Well this is a guess so I'm not sure, but I think Sangwoo's mother somehow saw her husband in him, so she kinda got sexual arousal when she was with Sangwoo as a teenager, which reaaaally could have shocked Sangwoo a lot. And when he said something about how honest children were and they couldn't lie, I think he somehow rejected his mother. Well, I cant figure out what comes next so we'll have to wait for the new chapter :'>

.
.
.
.
.
.
.
Well, Sangwoo normally only kills women (except for his dad and that one guy from the gay bar but that was only to test Bum) so it'd make sense that his mum did something to him. But I'm not sure either. Maybe these sexual undertones were only there because he imagined Bum as his mom and he just had sex with Bum.
We'll have to wait and see.
Spoilers
.
.
.
.
.
.
.
Big surprise: things got worse.
Bum is still scared and delusional, Sangwoo is losing his mind (his hallucinations are getting stronger, he sees Bum instead of his mum and he's talking weird shit) and Seungbae is lying in his bed listening to a tape while being drunk and depressed.