Why do I only like girls who are uninterested in me, while I am not physically attracted to the ones who are?

OK so it seems that I have always been attracted to girls that either had no interest in me or only wanted to be friends. Meanwhile the girls who are CLEARLY attracted to me, I would rather remain friends with them because I don't have a physical attraction or felt an intimate connection. I turn 20 this year and have never had a true girlfriend. Are my standards too high? Have I possibly been deluded into aiming "out of my league" my whole life? Am I the only guy who has this problem? Should I just "settle" for what I can get, and hope feelings develop?