Lack of self-confidence

A woman who thinks she's ugly and boring doesn't feel like a wanton sex goddess and is incapable of understanding how anyone can think of her as one! It's only logcial: if you have no self-confidence, you don't see how the opposite sex can find you attractive. You transpose your insecurities onto them, and when you're with someone you're constantly plagued by the thought that he's bound to leave you for someone better.