I am afraid that she will be pregnant. She is the biggest mess. Also, her father has this weird attraction for her sexually, I am afraid. At 17, he would go into her room at night and give her back rubs, watch her undress, and she would ask daddy if he thought her breasts were too big. It was sick.
Emotional incest is characterized by poor boundaries between parent and child.
Children often feel invaded by their parent's intrusive behaviors or disloyal if they have outside relationships with peers. This doesn't appear to be a problem for your fianc s daughter as she is sexually active and wanting to move out with another male. The sexual overtones of this relationship is alarming and needs to be addressed. The other issue is your relationship with your fianc . I would strongly suggest the two of you do some premarital therapy prior to making a lifelong commitment.