Serious replies only please?

I have a problem and every day it grows deeper. My problem is I think I might be crazy/demented/ or there might be something just wrong with me. First of all im 19 years old and will be starting college this upcoming semester. I lack excitement for a lot of things is my main problem. I currently started talking to this girl, and let me just say shes Beautiful. I thank god our paths met once again....back then we were just friends, but know were dating. I know she loves me and I tell myself that I love her as well...yet deeply inside I know I really dont like her as much as I say..she calls me and I think twice about answering the phone. Now don't think this is a "love problem" because its not. Since I was younger I had a lot of friends...but I always knew I had some kind of social disorder because I could never maintain these friendships....Ive even been called a bad friend by this one girl because she said whenever I meet someone I seem like we have a great connection at first and then I give a 1% to try to maintain our friendship and sadly I know its true....my life started to seem rather pointless after I noticed I could get woman to sleep with me and id rather be alone than actually be with the girl....UGhhhh its Driving me to a hole which seems to get deeper...deeper theres many more factors to this unexplainable disorder I might have....all I know is my mind isn't thinking what it should be and I hate it...