You are such a good friend for sticking by this girl through thick and thin, although it sounds like she hasn't always been the best sort of friend to you. Chances are, you keep her around because she's good in crisis, or there when you need her, or has good connections at all the best spots around town. Because, seriously, there must be some reason you continue to deal with your insecure friend's disappearing acts and subsequent neediness. So first, figure out why you two are friends, then remind her of that. Remind her what a great person she is, too, and that she doesn't need a guy to define her life. If she's anything like my friends, she probably won't believe you right off the bat, but a good girls' weekend, full of wine and as far away from any guys or talk of guys as possible, might help do the trick. However, if you can't remember why you two are friends, and if her rollercoaster of a dating life is really running you down, maybe it's time to move on. Not all friendships are forever.