What do i do now, shes dumped me twice.....?

If she's used to being lunged then get someone to lunge her while you ride her instead of just lunging her. If she's good with that then maybe later you can stop lunging. Don't do anything that you're not comfortable with because it will get to your horse and cause problems. It's probably because she and you are so used to it and when you first got on her the only thing you could think about was that you didn't lunge her. So you probably started doing different stuff. She can feel everything you feel. Do what you think is best...not your friend. You know your horse best!