New to polygamy. Having a hard time to accept it.

I have been dating this girl for almost 9 months. We initially only started seeing each other as a sexual thing, but with a few months down the road we ended up falling in love and got super attached to each other.
Shes been on an open relationship with her partner for the last 7 years. Long short story, in the last 4 months I relocated for work and we continue to date each other making time to get together and travel together. This only made our connection stronger. I am now, relocating back home for work and we will be close to each other again.
In the last few weeks, I have told her I’d like to do life with her and ultimately she would have to choose.
She is not attracted to her partner anymore and they rarely gets physical, which triggers me a lot because I can’t wrap my mind about her loving him and loving me.
Lately, she’s not being able to make a decision and asked if I’d be willing to compromise a few things to see if she can incorporate me in their life, which means I’d move in with them and see if we all can live together. I’ve been giving a lot of push back and my only requirement is that I’m ok with us living together but they would have to quit being sexually physical. I’m trying to wrap this concept in my mind and try to be open minded but I’m really struggling with it and starting to create resentment towards her.
Have anyone gone through something similar?