Coming at this from the other side - a partner who truly loves you will want you to be happy. Sometimes that means, heartbreakingly, letting you go, if there's no way to reconcile their needs with yours. (And sometimes it means there are compromises that neither of you realized were possible until you tried, of course, but you can't count on that.)
I said very often that my wife needed to transition more than I needed to be happy, at least in the short term, because I believed we'd *both* be happier in the long term. But if it were a question of her living a miserable half-existence to make me happy... well, really, how COULD I manage to be content in that situation over the long term!? For me personally, while I did feel that her transition was a selfish decision (in the sense of "centered on herself," not as a moral judgement/criticism), I also felt that it was one she was entitled to, and furthermore that I would be *more* selfish to force her to suffer terribly and permanently order to keep from hurting me temporarily.
In the end, you cannot live your life for someone else without paying a very heavy price.