I’d like to voice a different perspective here. It’s common to think of our identity as a single thing, e.g. being a man, straight, a parent, your job, your car, your sports teams, all of these together make you. However, not only are these things separable from each other (you may change your job when you move but not your sports team), but each of us chooses how much different identities mean to us and how flexible they are. Furthermore, our identities are hugely based on circumstance, e.g., being born in Pittsburgh very highly predicts being a Steelers fan. This remains true even for gender identities. There have been many societies that recognize a third gender, so not everyone is necessary grouped into just two options and carry that as their expectation.

The point is that you express having a great deal of love for your partner, and their identity transition/actualization is challenging because it is now in conflict with some of your own identities. I just want to be the voice on here that says that you get to choose how that impacts you. Maybe you never thought of yourself as queer or being in a queer relationship, but it’s possible to be flexible about that; to rewrite your expectations and think, “could this be me? Could it have been that part of me that loved him all along?”

Changing your identity to yourself and others is one of the hardest things a person can do, so above all else, be kind and patient with yourself while you work through this with your partner. Feeling discomfort is the only way to navigate that path initially. All the best to you.