Yeonwoo kissed him in his sleep, i.e. Yeonwoo took advantage of Taehwan when he was asleep. No Yeonwoo to be clear! I love him; he's so soft and sweet--and he didn't have bad intentions. But the fact remains that he broke Taehwan's trust.
In Taehwan's perspective, his close friend had taken advantage of him while he was asleep--then putting that together with his past trauma... While Taehwan is a jerk, I wouldn't call what he's doing trauma-dumping, as his disgust isn't exactly baseless.
Oops I mean "No Yeonwoo [hate], to be clear!" missed a word there ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄
so as i can see taehwan have a trauma bout gays but it still doesn't excuse his actions, i feel bad but its not ok to trauma dump