Out of control flirter leaves trail of destruction

[gabelee]

Just a brief self-sketch:

I guess I am a flirter, after a kind, but an unhappy one. I am considered fairly attractive by some people. But I also tend to "date down" with people who are less attractive. I've rarely dated people I would consider more attractive-- this does not work well due to my insecurities. Actually, insecurities plague all my relationships, but less so when I feel more confident about my looks. I generally do not make the first move, although recently I have been trying to do this more.

The problem is that when I am approached I usually respond really positively to try to get to know the person before making a decision as to whether I want to go forward with them or not, and this often takes a date or two. During the first times together, I really try to be positive and open, but there seems to always come a moment when the person will do some small thing that pisses me off and I break it off immediately. I do not know why I do this. I guess I like getting the attention but then suddenly will balk at a certain point, usually when my self-esteem is affected by a person's comment or behavior. As a result of such sudden switches, I have occasionally been labeled by disgruntled dates as "crazy." I am not sure why I do this, but I need to handle my dates in a better, more humane fashion. Any advice?