If you are the title holder on a car and your estranged wife is using the car without permission will she be arrested if the car is reported stolen?

I would guess that "if she was pulled over" the officer would run the tag. She would then be asked several serious questions and possibly be detained, but I doubt she would be arrested. I also think the police would have a few serious questions for you after they figured out what was going on. My guess is that this issue would better be settled in a divorce settlement.