Your girl sounds just like me. When I love someone I get lost in them but then I get scared of what will happen to me if I lose their affection. I will be a non entity I will only barely exist. To protect myself from this I hedge my bets by keeping other male company within easy reach. I have been in my current relationship for nearly two years and to this day if I feel insecure I will go on a dating site and chat up some random guy it has only recently I even understood why I was doing this.

So first off I would try to find out if she is aware where the behavior is rooted because until you have that awareness you just find yourself doing these things and cannot verbalize the reason why. I feel like bringing the issues into consciousness awareness is the first step in modifying the behavior. As for your feelings I would urge you not judge her too harshly this is likely a pattern of behavior she had had most of her life. I think if you are committed to helping her feel safe and helping her process and talk about her feelings of insecurity this behavior may never be repeated.