The worst thing in the world for you to do is try and teach her yourself. I will bet you anything you will have a new girlfriend real soon. Help her on the ground all you can, but when it comes to flying, both of you will enjoy it much more if someone else does the teaching. Just tell her you don't know how to fly good enough to teach her yourself and get an instructor to teach her. She will thank you in the end. I know from experence that it does NOT work.
Ed