I think people are forgetting how this relationship started. Ho-in knew that Chunwoo is still so deep in love with Taesoo. Chunwoo is also aware of that. They both felt a connection between them and Ho-In had offered himself whole heartedly because he knows the relationship between Taesoo and Chunwoo is tragedy waiting to happen and he wants Chunwoo to get out of that as soon as possible.
In simple terms:
Chunwoo: I am just going to hurt
Ho-in: I am willing to gamble
When he figured out that Woojin must have told Chunwoo something he knew his sunbae is gonna call it quits. He knew Chunwoo will not let him get hurt further.
So, don't be too harsh on Chunwoo and don't think Ho-in was stupid to do all these in the first place. I am not trying to invalidate either one of them. If only our heart and brain always agree with each other, oh how wonderful this world could be.
