Gomphus, welcome to PC Psych Central. I think you are wise not to point out her issues. That can be intimidating and experienced as hurt and judgment by the person for which you observe behaviors.

I also discovered the more clearly I see the other person's fault, the more certain it is to be mine and one which I have trouble dealing with. Another reason to withhold pointing things out.

Finding common ground is important in relationship building. You can try to define that in your notebook or discussing with the other person. Most relationships have only a small area of common ground. Each person decides what kind of people to have a friends or companions. Maybe just having someone is what is needed at a certain point. Sometimes when this is no longer enough, we start to focus on differences.