Serial killer that is infactuated with his prey?

Girl who sees scents (You won't see any handsome serial killer anywhere than in this drama lol, there is main hero as well who is a police, with a bit of romance with heroine)

Signal (There was one serial killer, again handsome, who didn't know he was in love with a girl, because how good she was to him, but their fate was so tragic, gives you heaviness.)

the new drama Born Again has this trope.

I think psychopath diary sort of fits this description. Like a pushover guy witness a murder but somehow he loses his memory and finds the diary of that psychopath/murderer from the murder he witnessed. So now pushover guy thinks he's a psychopath and tries to act like one, while the real one tries to get close to him. It's super hilarious.