I am obsessed with my bf I can't even function?

Pretty much for the past 5 or so years I have been a loner. People find me very outgoing and friendly, but they just don't like to hang out with me at all. I am a sophmore in college and I have literally no friends. I have hobbies and I go to church and see people there, but people just don't like being around me very much. So I am exptremely lonely. But within the past two years I have been with this one guy that i am madly in love with. I didnt go out with him our of desperation, becasue plenty of guys asked me out and I said no because I didnt like them. But I love this guy. We are like best friends in the world...and I dont have anyone else. We talk aobut getting married all the time and everything. When Im around him i feel like I'm on top of the world. But as soon as we part from eachother....I can't function. I am a mental blob. I can't focus on school, and put any energy into anything other than him. All I want to do is be around him. It hurts so bad when I go without seeing him even for a day. Should I speak to someone for help? How do I become not so obsessed so I cant focus on my life?