3) Yoonbum and Sangwoo both die. (There a couple of ways for this to happen)
a)Yoonbum starts killing too. The are partners in crime. Get cornered by the police and are killed by them.
b)Same thing but they get cornered by the police and kill themselves.
c) One dies the other gives up on life without them and kills himself
There are other theories as to how this will happen but am too lazy to list them all
4) One kills the other. Yoonbum kills Sangwoo/Sangwoo kills Yoonbum
3) sangwoo gets caught and tried to commit suicide, but not alone, he tried to killed yoonbum with him. The police guy is the real guy who saves him at camp, the police guy who finds the concrete evidence that the murderer is sangwoo, save yoonbum. YOONBUM knows who is the one who save him and he didnt love sangwoo anymore and love police guy. the police guy brings yoonbum away they get married and live happily ever after. sangwoo die and go to hell
police guyX yoonbum
save this as this is going to be reality!!!

1) The police men will be killed. Yoonbum and Sangwoo will stay together. Maybe Yoonbum will start to like killing (or is imagining to start liking it - as he is so desperately in love with Sangwoo.
2) Sangwoo is caught by the police. Maybe Sangwoo and Yoonbum will keep in touch whilst he is in jail. I can't imagine Yoonbum not returning to him.
These are the ones I can imagine! Is anyone thinking about other endings?