Don't be too kind of your words, just say it. He's awfully toxic.
He blackmailed B** into this whole relationship at the first place, never know what 'no' means, he's crazy jealous, and try to separate b** from everybody to keep him for himself... the manipulation, and the fact he makes b** feel guilty all the time is just the cherry on the top.,
(Yeeah yeah, it could be worse, at least he's not evil or violent, I get that, but still... he"s a HUGE red flag.
So remember kids, even if you feel it's 'cute' compared to other stories, because average BL-s are full of psychos and crazy rapists, the reality is that this behaviour is totally unacceptable, so you shouldn't shake it off saing "ahhit's not violence". it is. It IS domestic violence, and that absolety means Yeonwoo IS a RED FLAG.
So if your partner is like Yeonwoo... run!
Don't hink you can handle him, don't try to satisfy his needs, don't try to change him, and especially don't try to change yourself for him, just RUN and never look back. It's the best you can do in this situation.