My husband and I have our own bedrooms, and sometimes he sleeps with me because we started out that way. His room in our house has reverted to the way his room looked when we first met... I would venture that no woman would WANT to sleep in there, but I did...
If I were involved with someone who regularly shares a bed with their live-in partner, I'm not sure I'd WANT to sleep in their bed unless I had some sort of independent connection with the other partner, and then only if the other partner offered that option.
If I had another partner who lived alone, I'd probably go to their place to get it on... But this is all hypothetical when it comes to my situation.
Of course, I'd talk about it with the other people involved regardless of what I would want in my own ideal world.