All I can say is that for me this is mostly a theoretical issue for discussion. I am open to exploring how polyamory would work in practice, but I've never had multiple sexual partners at the same time. From the responses I'm getting to things I say, it's as if I've triggered some primordial defensiveness regarding privacy rights. If the topic is as sensitive as it seems, it tells me that there are some deep-seated fears about what could happen if you were expected to openly field questions about your sex lives. Personally, I don't like it when people interrogate me about things I don't want to talk about either, and that's not just limited to sex. However, I can still reflect on the fact that the reasons I am sensitive about being asked about certain things is because of how I think the information could be used to harass me in some way or otherwise manipulate me.
With sex, I think it is a shame that people feel like they can't talk about what they feel or do with other people with those they love. A big part of the joy of intimacy, imo, is being able to talk about things you wouldn't talk about with just anyone. It's nice to be able to open up and this thread is almost making it sound like people are having to sacrifice intimacy/openness with one partner to be able to have sex with another. Whether or not that's legitimate, it's still a sacrifice of sorts isn't it?