Responses
You're right. His only purpose to get close to ML was his obsession, she became only a reason only a facade to stalk him.
He's mentally ill. I just don't know what to call his condition.
I think the issue is that MC already have a mental illness or is in a spectrum, as well as the ML. Like since the beginning he knew what kind of person ML was and still fell in love with him to the point he didn’t want to expose the ML when he had the opportunity. Like, even doing all those stuff about revenge for a friend that had an illness and passed away makes no sense.