You should feel free to tell them exactly what you wrote here. I mean, if you can share your body with them, you should be able to talk to them. Personal boundaries are important and everyone has them. Therefore your partners need to respect those boundaries, not get huffy about it. If they get bent out of shape, it's their problem to deal with as grown-ups, not yours. You write, you need privacy, you like things neat. End of story - just tell them point blank. Why is it a problem for you to express your needs?
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein