Why am I COMPLETELY hopeless with girls?

I worry myself crazy when I have a crush on a paricular girl because, for me love isn't a game where as most girls think it is, it seems that as soon as they hear that you like them they immediately take control of the situation, ignore me, pretend I don't exist or only talk to me when I talk to them. I don't understand why awkwardness seems co complusary when there is chemistry between a man and a woman.