I don't really get what his cousin (?) is trying to do, protesting like that or is that some sort of anxiety/depression?  If not, then if you want to change something/not be involved with your family you should be independent etc, I don't know his goals but he only brought trouble for Jaeha this far. 
I mean, he's still a kid, but if he sits at home every day he should have plenty of time to realize everything😅