That's awesome to hear. I still strongly advise separating things like this as much as you can, like by saving play for spaces separate from an all-volunteer after party. If someone is uncomfortable with people getting big-time sexual in that kind of setting, that means they just have to leave (or suck it up), which blows at best, and at worst, feels a lot like people putting you in their scene without your permission. On the other hand, if you take that somewhere private when you want to do it, that doesn't have to be a possible issue, you know?
I do also want to add though, that a couple of bottles of wine for three people is actually LOT of alcohol, were it all to be consumed. So as far as consent is concerned, especially since it sounds like this does really matter to you, that if people are getting drunk, which they would be sharing a couple bottles among three people, you're already stepping outside of a situation in which anyone who is can fully consent. Obviously, in practical life, there's this wide scale/range that goes from having a sip of booze and being blackout drunk, but we really do get to consent-is-iffy pretty soon once people are drinking more than a glass of a thing, particularly if they're binge drinking (drinking a lot of it fast, which is also dangerous in other ways).
Again, apologies for the unsolicited advice, but this is just one of those things I have a pretty long view on (I'm old), and have also been a person in those kinds of spaces/situations other people often tell about their negative feelings and experiences, or who people talk to before they bring complaints or issues to organizers.
In terms of what to say to G, how do you feel about just texting and asking if she has a few minutes to talk because you want to check in with her about a thing? Then if she does, you can just say what you did here: that before you are in the same space, you want to make sure you're not making any assumptions about what happened with the two of you last time. You can say that you're feeling excited to see her, and have been thinking about seeing if she wanted to pursue more of the kind of interaction you had last time this time, but don't want to make it awkward when you're in her space by just putting that in her face without some advance ask. How does something like that sound?
Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has. - Margaret Mead