@Paulllllll,
I don't understand her reasoning, if the situation was reversed wouldn't you want her to be where she is the most comfortable? I understand it's an honest answer, but life doesn't come with a warranty. This might sound crazy, but she really can't assume she will live longer than you despite your prognosis.
Is she afraid your family will shut her out? Is that a possibility? I don't remember if you mentioned parents, but if my grown child was sick, I'd want to help out. If she changes her mind and decides to move with you, is there a reason she wouldn't be able to return to where she feels most comfortable when the end comes? Is an approved leave of absence possible at her workplace?i know the doctors have given you a grim outlook, but many people do so much better than their doctors thought they could. I'm sure being closer to your family would be a big plus for you. I know this is your decision, but if someone told me I'd have only 6 months to a year left, I would be sucking up every ounce of pleasure I could, I'd spend time with my friends, my husband and son and grand daughter. I'd fly my nephews in for a beach vacation, oh hell I'd pack as much living as I could into whatever time I had left.
But to be fair, I'm probably a lot older than you, and I've lost many family members and friends. We all say we should live every day like it's our last, but we tend to slip back into old habits, worry about things that really don't matter. But you know you don't have as much spare time to worry about nonsense. Give yourself a week or so, see a therapist (it might be good to have a neutral place to discuss your options) but then do what makes you happy or at least more content. I truly wish you didn't have to make a decision, but I also hope for the best for you. Good luck.