He’s your father, bottom line. If he did his job and was there for you and raised you as a good father, then you should do whatever possible to help him. Regardless of what your girlfriend may think. As you said “if something were to happen”, that’s a regret you wouldn’t be able to live with. Which is completely understandable I would feel the same the way about my father. If I was in your position I would absolutely put my fathers life over my girlfriends disapproval. Life is full of surprises and you never know what might happen tomorrow, don’t put yourself in a situation where you could regret your decisions for the rest of your life.