I am 29F whos been seeing this girl(25) for a year and a half who has a boyfriend of 6 years. We are not officially gfs and took took a six month break because he gave her an ultimatum that if she stays with me, they will need to break up. She lives with her parents, sister, and boyfriend. Her parents are very traditional who suggested this should stop and needs to make a decision. They feel this way because she tends to hide me from the bf and see me behind his back, although he knows of me. He doesn't know how much time she spends with me. I did not know this until she confessed it to me a week ago. Since he knows she's seeing women, she doesn't think seeing me is breaking any of their rules. She mentioned she would like to switch from dating him to being monogamous with me. She told me there are things missing from their relationship and she finds our relationship fulfilling enough.
Some of the things she struggles with is
-Feeling bad for leaving him when she doesn't feel he did anything wrong
-Feeling she can't leave him because she has a loyalty to him
-Being afraid of leaving a heterosexual relationship to a lesbian relationship, feeling like she would be judged and is officially a lesbian
-Wanting to leave this relationship to be with me but doesn't know if she's ready
- He allowed her to be with women so leaving him for one would be a betrayal

She wanted me to meet her family first to see if we'd get along because her family is important to her. I met them and everything turned out well. Her family was supportive of her relationship with me if she chose to be with me, which I felt relived because I was worried they wouldn't approve of a same-sex relationship. Oddly, they were helping her see me without letting the boyfriend know as they think I help their daughter a lot and appreciate what I've done for her. Everything was going well but she was constantly talking about how leaving him would be hard for her since she is throwing away 6 years.

I thought I should get a couples therapist to help out with this further if she truly wants to be with me. I do want to be monogamous with her as well. Everything was completely fine until we entered the session. We spent new years day together and I was able to take her out to dinner and share gifts with her. Rather than working through issues, she popped up with a decision. She told the therapist and I that she talked to her boyfriend to confess her feelings for me, who told her that she's allowed to be with women and have feelings (but not with men), however it is not fair to him for her to leave him because they've been together for 6 years and I am just using gifts(love language) and taking her out so I could steal her from him. She agreed that this is unfair to him so let me and the therapist know she has chosen him. She started questioning that I am only doing nice things for her so she can leave her boyfriend. I've defended myself, and said I don't give her gifts to steal her. It is just how I show my love. I care about her and pay all her expenses including her psychologist and medications. She said she would like to be in a relationship with us both, but I am monogomous... She explained that if she stays with him she can continue to be polyamorous and seek out others on dating apps.

I feel like she used my session to dump me unexpectedly. I was feeling quite awful after feeling we could work on these issues through regular couples therapy as she wanted to be monogamous with me. She messaged me the next day and said she still loves me and is here for me, and wanted to know if I would be in a relationship with her while she stays with him. I agreed because I didn't want to lose her. She keeps changing her mind, not knowing what she wants. Some days she is hot with me and then she will be very cold. It's hard for me to let her go