I have never been shy about the fact that I am not remotely about the group sex. I am a pure monogamist in my soul, a subject that I have addressed frequently on this blog. There is often a prevailing expectation within the BDSM community of some form of nonmonogamy, be it polyamory, open relationships, or casual threesomes at the very least. It goes hand in hand with the expectation of bisexuality, particularly among submissive females.
I have encountered those in the past that believe that as a slave, I should fully expect any owner I have to have sex with others or for him to expect me to have sex with others. The expectation of monogamy is seen by these types as "controlling the owner's dick," because, I mean, God forbid monogamous men/owners exist too.
I'm always very up front with potential partners about my expectation of monogamy and my utter disinterest in nonmonogamous sex. I'm not bisexual, so MFF would be utterly pointless, and I can't even stomach the thought of having sex with more than one man at a time, so MFM is out.
However, in my early days in the lifestyle, I did come close to an MFF threesome twice. I've never really counted them, as we didn't really have sex.
The first occasion was actually both my first kinky experience and my first sexual experience. I've mentioned the couple that initiated me into kink before. The night consisted of my first kiss and my first beating. I however remained half clothed the whole time like the terrified virgin I was. The couple did have sex with each other while I laid next to them in the bed, but I don't believe that counts since I wasn't really a participant.
The second occasion was with my first dom, who pressured me into asking a friend to have a threesome with us. We ended up doing a number of things, but no one ended up having sex because my friend and I weren't nearly as comfortable with the situation as we might have hoped.
It was largely through these two encounters, call them threesomes if you want, that I confirmed my heterosexuality. It also reinforced my general possessiveness. I don't like sharing my owner. I'm utterly enthralled by my partner. I have no extra space to worry about someone else in the mix. Sometimes I barely have the attention span for one. I have a tendency to go a bit brain dead when I'm being touched.
I'm really not one for sharing attention on either side of a sexual encounter. Is all mine.