Hi. I went through your query in detail and can understand the frustration that you must be facing. However, considering the situation you are in, it's vital to take decisions. Given the scenario, you will always face such situation if you don't deal with the current head on. Talk to your partner regarding choosing and sticking to it. Only if you both are ready to work in it, you will be happy. Else, it will only give you further sorrow. So, in that case it will be pertinent to move on in life.
Next Steps
Talk openly with your girlfriend. Go for couple's therapy with a Psychiatrist if required.