I'm staying in a relationship in which I am deeply unhappy because I fear this is as good as it will ever get for me and am also afraid of moving back home and starting over again.
It sounds like you really do not want to stay.
I'm kind of afraid of answering this question because I don't want to have any fights in the relationship, but yes she treats me very well.
You shouldn't stay in a relationship due to pressure or compliance. If the person is abusive then you stay far away from them.
I don't think she is abusive and I'm staying with her since I want to.
The unhappiness you're feeling about the relationship now will only increase if nothing changes. You shouldn't settle for an unhappy relationship because you're afraid to move on. At the very least talk to her and try to improve things.