I've learned so much here from everyone, the GGs, the CDers, the TSs, the staff, and everyone in between, lol. I can't say there is a section that I prefer over the others, although in times past when I've poured out my heart, I did this in FAB and got amazing support from the ladies.
But, I've also gotten amazing support from the other ladies in this forum too! We have many, many remarkable people here.
I would not feel threatened if the activities were with groups of people. I wouldn't feel threatened if the meetings were with just a single GG, provided they weren't arranged without my knowledge and if there was also an open invitation for me to join my SO and this GG (if I wished to do so). I would have an issue if my SO preferred to meet this other GG without me, or without wanting to tell me about it until after the fact, especially if I had met her and felt she was after my SO.
I'm not normally a jealous person, but if I ever got a bad vibe about a particular GG that my SO had befriended and I told my SO this, I would want my SO to respect my feelings and prioritize them over wanting to continue meeting this other GG. :p
My SO is always the same person to me. Always, no matter how he or she is dressed. I don't know how else to explain it other than I see all of my SO's gender expressions as being a fundamental part of him/her, just as much as basic personality traits. It's not about binary gender for my SO or me.