Maybe someday she'll rememeber what a good frind you were to her. She obviously doesn't love you in the frantic way young love should be. I am sorry for you but think for a minute:
What if you were married with children and she decided to up and take them back to her family with her? WOW talk about abandonment! With her mindset there is just no way this relationship would be anything but toxic for you.
Thank goodness you will not have a lifetime on that roller coaster ride.