You clearly haven't been paying attention to the fact that the man has been behaving completely outside of his normal conduct, and keep in mind he's in charge of a type of gang and he doesn't really know how normal people are in relationships. He did all of his own volition because he has been growing genuine affection for the mc. If anything the mc wasnt even trying to get that attached to the ml. There was no coercion or manipulation from either party.
nobody is shitting rainbow and glitter for this man, the fact is that he’s never once been horrible to the mc apart from that one time in s1 where he told yeomin not to expect anything more since then we can see he genuinely cares for him otherwise he wouldn’t have “beaten his only family to a pulp” his only family who is an abusive, absent father mind you. yeomin is aware of what he’s like and that he’s trying to control him to keep him close but he doesn’t know the rest of it, knowing his character though he will stand his ground. you need to give the guy a break he’s the only one that truly cares for him,
Yesss I love that everyone come together to tell someone who haven’t even read the whole manhwa that doesn’t understand right from wrong. And we can all agree that our ml is getting better and better at expressing his feeling even though it is slow and small but still there is some progress. (=・ω・=)

Imagine saying ILY to the man who secretly manipulates your school life, beats your only family to a pulp, is the reason behind your bankruptcy in the first place, doesn't respect your personal life, belittles your achievements, and instead of saying ILY back says : so many people love me blah blah ...
Y'all need to stop shittin glitter and rainbow for this type of male ┑( ̄Д  ̄)┍