Ah, so the "penis" word pops up (as it were!!)
If the GG enjoys s*x with a man, then her SRS partner is asking that she totally compromise that part of her life.
Fair? Or not .... Or does she take a lover? It's fair to ask - I might !!
Going through SRS means that the man becomes a woman (in this forum, anyway). That means the GG is now in a relationship with a woman.
Does that not challenge the GG's sexuality? And does she not have the right to choose what she wants? If she wants to have a 'relationship' with a woman, fine. Her choice. But it's HER (the GG's) choice.
I think that time together and age comes into it a lot as well. Been together for many years & built a stable life together? I would be more likely to be closer to a "maybe" than if we'd only been together a short time and I still had my hopes & expectations e.g. children etc.
PS. A relationship with a man is much more than physical - I can't explain the connection & excitement that I feel, but it's definitely there and I can't deny that part of me. I'l bet a lot of GG's agree with me ....