Its called a distinct lack of self confidence and distinct lack of self esteem.....
(Don't worry, I am seeking psycratric (sp?) treatment!).
I think it all comes down to how you deal with life, bullying, stress and the breakings of relationships. In my case, I don't fair very well, in fact, I'd be more inclined to do something bloody stupid than sit out and cope with it.

@ horribleperson
After reading your comment again (I thought at first that you would die for them), tbh, that could be seen as a threat. The kind of person I am, I would never say THAT sort of thing to anyone. (Unless they tried to kill me.)