Please help me with this weird problem that I have while dealing with girls?

I'm 20 and in college. My problem is that I feel that somehow all girls on this planet are connected and if you misbehave with one the others will eventually get to know it and stay away from you. Thus I end up wasting a lot of time and money on girls that I don't really want to date. If a girl I don't have a crush on asks me out I just cannot reject fearing that the girl I like might find out that I disappointed someone and think of me as a jerk.