I don't love a threesome. I instantly go into hostess mode, and worry too much about my partners to really relax and have fun. "Are you too hot? Should I open a window? Can I get you some water? A condom? Has everybody cum yet?"
Fly and I just had our first FMF last week. I had done one before, but he had not, so it was a big deal for him. He found a woman online (I was skeptical, but she turned out to be really nice) and the three of us got together. Turns out she was WAY more into me than him. It's not that he got totally left out, but I definitely felt like he didn't get as much attention as I did. I felt really bad, because this was supposed to be his party. To make it even more crunchy, she and I have been texting and emailing, and this may develop into something between her and me.
All this happened despite the fact that Fly and I have had dozens of conversations about what would be ok, what would make us unhappy, how we would behave during a threesome. I think even with the best of intentions and ample communication, threesomes can be a bit lopsided. Luckily, Fly is cool with how everything went down, even though it wasn't his ideal. But it still makes me feel like a bad girlfriend.
I think it's pretty important that the OP needs to chat with her primary and lay some groundwork before y'all try this again. Sometimes people get caught up in the new and shiny, and neglect their partner during these situations. That was something that worried me, and I'm fairly adamant that I'm not going to be the wallflower at the threesome. I personally need the sexual reassurance of being desirable to my partner, and if he wants to focus on the other person then they should just get it on and leave me out of it!
You absolutely deserve a fair share of the attention, and some patience and compassion while dealing with the fallout of what happened.
Magdlyn, I agree with a lot of what ThatGirlInGrey says. I think it's great that the Ginger wants to strengthen his relationship with Miss Pixi, but if that's the intent of the encounter then he needs to include you in a conversation about that, and ensure that you know what to expect. A heads-up prior to the moment was definitely in order.