There are no guarantees that any relationship will last. Maybe she needed to go through those other relationships to see what she lost and resolve herself to stand up to her parents. Maybe she'll cave in to them again. You won't know until you know. You have to decide if being with her is worth the risk of getting hurt again.
Have you considered that maybe he enjoyed the HJ with you so much that it's kicked his sex drive high and that's why he is doing it again?
There are no guarantees that any relationship will last. Maybe she needed to go through those other relationships to see what she lost and resolve herself to stand up to her parents. Maybe she'll cave in to them again. You won't know until you know. You have to decide if being with her is worth the risk of getting hurt again.