Our own experiences have varied. We have had a serious FMF relationship as well as a semi-serious MFM relationship. In addition, there have been a couple V relationships. Each situation was completely different. In our FMF relationship, we each had a very different relationship with her, and never had a threesome together. People got along in different degrees. In the MFM relationship, it began between the two of them, but I had already met him, and was comfortable with him. By the time we had our threesome, there was already a certain level of trust and friendship, so it was a small step. In that relationship, there were never any negative emotions between the three of us, and in that regard we were very lucky. We just had a great chemistry. In our Vs, we haven't always been as fortunate. What we have discovered through hard experience is that if anyone in the mix is uncomfortable with anyone else, we do everything we can to iron it out right at the start. If, after lots of kindness, humor, affection, communication & reaching out, the discomfort still exists, then it's just not going to work, no matter how badly we want it to. Sometimes one of us just gets a bad vibe about somebody, and can't seem to shake it. Since jealousy hasn't really been an issue for us, we always listen to each other if one of us gets an intuition about somebody new. We've learned to trust each other on this, and it has paid off. We never say, "Don't see so-and-so", but we might talk about red flags that we've noticed. Basically, if it is going to be something long-term, then everyone has to be friends (at the very least), and be able to communicate freely with everyone else involved, without a go-between.