This does not sound like a problem to me.
First, if you need to go, then you can have a pleasant 15 minute walk to the train station. Walk, Ride, Relax.
Second, if your girlfriend is also close to retirement, then in a short time she won't be leaving with the car and you can continue to enjoy the days together and the quiet evenings together. That is unless the girlfriend is much, much younger which may mean you need the rest during the day.
Third, getting another car is easier than getting a different house.

Just some thoughts . . . good luck with your dilemma.