Paul is holding the notes and his mind was astonished without knowing what has been done to his wife and who sent this note to his wife. And he got an idea to revenge.  So the future episodes, he just hire a detective to try to dig this thing out

Paul has so many bad things on his mind. So when he interact with others and other people may feel he give them creeps.  Life is very much like a mirror. When you look into the mirror, and the mirror will look into you and how you look into the mirror and the mirror will look into you the same way

Paul started to believe, there must be something planned by Edie, to take his wife away from him, and he decided to revenage.