The fewer waves you make, the fewer waves they feel...
I have never had any SO (wife or girlfriend) wind up being anything but helpful and supportive - in the past 30+ years.
They have never said, "Yippie, you were dresses!" but they have always said:
"OK, so why are you telling me and what am I supposed to do?"
You, my friend, need to answer the question they most want to ask:
"Are you going to be weird about this, or, can we add this to our list of his/her/our activities and continue on the course we had?"
If you're heading for gay bars and gay sex - which seems to be the worst fear - then say so. If you're not sure, say, "I don't know... I did/did not do that before so..."
If you're going to go "all girl" on them, they can get the real deal, a lesbian lover, down the street. But, they may not want to do that at all. If you do, and they don't: "See ya!"
People in relationships put up with all kinds of things. Drinking, sports fans, ski nuts, Wednesday choir practice - "forever," and many other things.
I find that if you can manage to do what she expects you to do, be there FOR her, almost any other interest can be worked around.
Think less about problems and more about living happily.
If she has a itch - like wanting to go on vacation with her family - you be there to scratch it and go along happily.
You stick with a plan like that, you're gold if you want to sleep hanging from the ceiling in a vampire suit.
"Yeah, he's a nut. But, he's my nut."