Search Results: grabbing a girl's butt

this guy in my college never leaves me alone! he will always be by my side. when another guy looks, talks and/or touchs me he will go off on them and then grab me and pull me to him. for my sessions he comes in sometimes to "check up on me" and he isn't even in that class. When he looks at me he has this weird look in his eye and he looks at me like i'm the most precious thing in the world. i know he likes me because he told me but i don't like him back because he scares me. on my social media he likes and comments on my posts and a second after i post them. he will post stuff on my wall on facebook that says stuff like "oh you are such a beautiful woman and i wish you were mine." he also wants to know where my apartment is really badly he will ask for my address every chance he gets. He touchs me all the time too. he will touch and stroke my arms, massage my shoulders, put his arm around my shoulders or waist, will put his hand on my butt and "accidentally" touch my boobs. But then he will also slap my ass and ask to touch my boobs and of course i say no. I have told his guy to back off multiple times but he does not listen.
Why is he doing this? What is he trying to do? Guy, do you do this to girls or would you ever? What should i do about him?