Forgiveness is about understanding that none is perfect. First step is to admit that you are not perfect, and that other people may perceive you in a way that you yourself don’t see yourself. In your particular case, it sounds like you are not willing to listen to your girlfriend’s opinion about you and your behaviour. The fact is that even if you don’t agree with her, and even if she is not telling you the truth, it does not matter. What matters is that she does not see you as a suitable partner for her right now. If you were in a relationship with someone and suddenly felt that you no longer belong with them, what would you do? Maybe you would handle it in another way, but ultimately you either would end that relationship or stay with them to be unhappy ever after…

So, if you want to forgive her, realize that she owes you nothing. You owe her nothing. But you both owe yourselves to be happy. So, if you want her to be happy, let her do what she need to do. And let’s say you could wake up tomorrow and, magically, everything is perfect, and you feel happy. What would be different about that day? What would you be doing, who would you be talking to and about what?