You're afraid. Your insecurity adds to your fear. Once you accept the fact that someone out there finds you pretty, kind, and smart enough to pursue something with you, I think that fear can begin to subside. You are your own worst enemy and the only thing in the way between the single life and being bold enough to venture forth. Allowing yourself to get that close to someone involves facing the fact that someone could get hurt. No relationship is perfect, and anyone who claims to have a perfect relationship is a damn liar and should be ignored.