I think you read another story. And wait for the flashback for more details.
Even if I go back, it's not the right thing to do to sleep with another person that is in love with you just because you kind of like him while you're deeply in love with someone else. It's OK if he sleeps with a person who's only for the sex.
the other person agreed and knows that he is in love with another. Ho- In knew that, very well. Is no innocent. He want fuck Chunwoo so bad, is so horny for him. And to forget someone he is in love with, you need someone else.
If Chunwoo really likes the redhead guy then tell him that he's in love with him, it's not a great look going around playing with other people's feelings. Why does he need to sleep with another person just to make sure they're straight or in love with him. This is the reason why I hate some good-looking people they take advantage of other peoples feeling and play like a god.