Why am I not having much success with girls?

I'm 16 years old, im an alright looking guy, nothing to write home about but im relatively attractive, and more so I've been told I have a great personality, all my friends and family know i truly care about them and i am pionate about everything i do, I'm very confident, not y, I have a pretty laid back personality but i have a great sense of humor and I'm alot of fun to be around. I always treat women respectfully, and maintain good frienships with plenty of girls. I have plenty of friends, I'm in good shape, im about 5'11 and 142 pounds, and im a runningback and cornerback on my schools football team. The last girl i had a "thing" with said that she didnt deserve me and that i treated her perfect, and i actually brought her to tears over a romantic thing i said to her. A few weeks later she seemed to all of a sudden lose interest in me. Before that girls never really seemed to notice me and even now still girls dont seem to be interested in me as far as relationships go. Is there something really wrong with me?