One thing I really appreciate about this story is that it shows a behavior that is sometimes depicted as very romantic (I don't want you to have anyone but me!) and displays it as the controlling ego-centered and abusive behavior it actually is in a lot of situations.
This top is just as mentally ill as Woojin, its just expressed differently. Woojin can't stand (his perception) of being alone, and this top can't stand (his perception) of being out of control/abandoned.
Both of them of them meeting and making each other worse is good character writing and a good understanding of the pitfalls of unresolved mental health issues. And I wasn't expecting that out of this story at first tbh!