Hi thanks so much for being just so patient.
You know I really do admire you and your wishes for your girlfriend and I totally do get where you are coming from but even if and I say this very very carefully and candidly even if her sisters were physically beating her daily she should not be behaving as she is.
Its so clear that you love this girl so much that you are making excuses for her. You are so loving of her. but no.
Your girl is confused because she is confused. She is cold and distant because she is confused and she is making poor choices and she is using her sisters poor behavior as an excuse or you are using her sisters poor behaviors as an excuse because you love her as you do.
Heres the thing when families rally against a partner it draws the two together not apart. Its a universal, it never varies and I know about this very well because it is exactly what I do in my practice and I have been doing it for over thirty years.
The expert answer to you is: let this one go and find yourself a woman, a grown up woman and not a childish girl who is going to treat you so much better and reciprocate your wonderful feelings.
The answer you just wish to hear is: Keep feeling sorry for her and her problems with her sister until she finds someone else and dumps you.
You deserve better> I do not buy her claim that she is so absorbed by her sisters jealous and extremely poor behaviors that she is turning away from you
AND EVEN IF THAT WERE TRUE
you do not need to marry or become further involved in a family where people treat each other this way? How ridiculous is this?
Leave her. Move on. Find someone who appreciates you.
Men like you who are sensitive and caring are rare. very rare indeed.
I know. I know its not the answer you wanted to hear but I am an expert and I wanted to give you the expert answer even if you did not like it and would not pay. I am an expert and I am telling you the truth.
Having said this.
You take good care of you. You are one decent and caring guy.