..."put our baby through enough"
while Seul pushing the boundaries atm bothers me somewhat, I wouldn't bash for rejecting Joon when he wasn't even sure of his own feelings. We're talking about a man who's been straight his whole life, who's drunkenly kissed a guy. He was confused.
Also, rejection hurts, and rejection is normal. I doubt it'd been his intent to make Joon sad--plus, he doesn't even know that Joon took the rejection badly. The readers, as bystanders, know, but the characters themselves can't see things as clearly as us.

High key worries me that everyone is saying that this is cute like???? He’s acting so selfishly towards joon when it’s so obvious that he is uncomfortable. And the way he looked so pleased when he realised that Joon was probably crying because of him?! What a psycho! Hasn’t he put our baby through enough :(( I don’t like him one bit