Set a standard for yourself. I'm not talking about a minimum bust-size of woman you'll get involved with (although I've met some dorks who actually think this way). I'm talking about emotional manipulation. Human beings are inherently insecure creatures, and the vast majority have a hard time dealing with feelings of potential abandonment. Many will resort to control games to construct an emotional security blanket and I'll bet that's just what your lady friend did, whether she was conscious of it or not.

I've been subjected to that kind of manipulation any number of times in my past and I absolutely refuse to respond to it. When you do that, their control-gaming either gets more desperate or it stops. Take responsibility and explain to your partner that you won't put up with manipulation, but you're always willing to talk and that her feelings are important to you. Tell her that she needs to trust you, and if she doesn't it makes for a very shaky foundation for a relationship.

Give her time and some wiggle room, more rather than less if you really think you have something special there. But if that wiggle room gets used up, leave. Don't constantly reward her with yet another chance or you'll end up teaching your partner that her behaviour is acceptable.

Two things to remember while you're doing this: you're not perfect either, and you must be okay with being alone for the rest of your life. If you firmly believe that you can't be happy without being cleaved unto another, you're setting yourself up for a potentially disastrous emotional rollercoaster.

My two Canadian cents, which seem to be worth a little more these days Stateside. :)