I'm on team "Haejoon is the one who decided to go and live in the dorms, in the first place. Leave him alone."
I'm still pretty sure there should have been other reasons his mom divorced the dad, just saying. Especially since the fight might have reminded him of something that he may have seen when he was younger. Just... think about how the mom was stubborn in raising him on her own, if it was under also her own terms (I was also under the impression that her thing about ghosts also made her some sort of pariah, iirc when we revisited Haejoon's childhood). I don't think it was just about debts.
I agree it's also too embarrassing seeing two adults (who were absent in Haejoon's life up until recent) fighting for him as if he was a 5 year old child.