How to deal with infatuations and Asperger's Syndrome?

Right now I have about three or four infatuations with girls in my university happening. I am 21 years old; and unfortunately I have struggled with infatuated emotions for most of my life. I really don't like having to be chained to infatuations, which can lead to other emotions like jealousy or frustration. I do want to emphasize I am not a creep or a violent person; I just get "stuck" on a person and if that person has a boyfriend or is in a higher social strata than myself I get butterflies in my stomach and get very agitated. I have a crush on a girl who right now has a boyfriend, and I want to enroll in a law class at uni that she will be in but the only reason i want to enroll in this class is not out of intellectual curiosity but my infatuation for my love interest. I want to banish these infatuations so I can move on with my life and not have an infatuations chain itself around me tighter and tighter until I can't move on. One girl I have had an infatuation with for four years and I don't know if my infatuation will ever dissipate. What exactly is happening in my brain and how can I remove this problem. I have Asperger's too, by the way.