As a person who has been a very similar situation, I would advise LW to seriously reconsider marrying this man at this point in time, and also would advise LW to consider moving out into her place, until dad and daughter can work things out themselves. From personal experience, the stepmother (or girlfriend) is very, very limited in what she can actually do to help the girl. All the love in the world from LW cannot fix the girl, fix her problems, or fix the relationship between the girl and her father.

Dad and daughter must work it out themselves and it would be best for LW to let them do it in their own time and space. Counseling for dad and daughter, jointly and individually, could help tremendously for them to address the problems the girl has in growing up and their feelings toward each other.

I also married a man who had a daughter who had troubles stemming from her parents' divorce. Mom leaving the home when the girl was 5. I loved my stepdaughter like I loved my own children, and I thought that my love would make all the difference for her and she would become happier. In actuality, however, I was in the way. What needed to happen was that dad and daughter (and mom) needed to work out their feelings and their relationships. It took years for this to happen.

In the meantime, I just complicated matters by feeling angry, hurt, and rejected by my stepdaughter. I finally had to detach from her as much as possible, while still being supportive of my husband. Our love for each other is what got us through this difficult time.

I learned to listen and keep my thoughts to myself instead of being judgmental and venting to my husband. I also learned that my ability to change anything in the situation was extremely limited. You can't tell someone to change. They change when they feel they must.

This was one of the most difficult periods in my life. If LW chooses to stay with this man and his daughter, she will have years of dealing with the daughter's issues. Obviously, she knows already that she is very conflicted about the situation. My advice would be to listen to her own feelings and be very, very cautious about moving forward with her relationship to her boyfriend and his daughter.