@Saltlife 98,
Maybe she keeps looking at you because she sees you looking at her and thinks that by looking at her all the time you are some kind of creep. But then again, how does she know you are looking at her all the time unless she is looking at you all the time? Of course, it could be that your looks toward her are noticed by her girlfriend, who is always looking at you because you are such a wonderful specimen of a man, and the girlfriend tells her friend about your constant looking, which results in her looking at you.
Why don't you just stop the looking and do something mature, like pass her a note proclaiming your undying love for her. (That only works if you are in grade school, so be careful.) If you are older, then why not actually stop looking and go up to her and talk to her. I mean, you will have to do that at some point if you hope to have a relationship with her, so you might as well start talking to her now.