This may be a personal quirk, but I firmly believe everyone needs some personal space, a spot in their home that is “theirs.” Much like Virginia Woolf’s “A Room of One’s Own,” but it may actually be a chair, a spot on the porch, a corner of the attic, or any place else that works. Unsurprisingly, introverts seem to place more importance on having personal space than extroverts, but I’ve known many an extrovert who had their favorite chair to curl up in while they talked on the phone, an god help the person who was sitting that chair when the extrovert wanted to call their best friend.
I don’t fully understand the psychological importance of having a personal space. I expect that this need is at least partly cultural, and people who grow up in more communal cultures will experience personal space very differently from those of us in the very individualistic US. I do distinctly remember reading a New Yorker discussing the way everyone in NYC public transit so pointedly ignores each other and never even says hello—a practice that many newcomers to the city see as rude. In crowded New York City, this “ignoring” each other is actually a way to create some psychological privacy, in a place where physical privacy can be near-impossible.
In any case, when polyfolk move in together, everyone will sooner or later lay unofficial claim to a spot in the home as “theirs”. if you are moving into an entirely new home together, this is usually a fairly smooth and unconscious process. Denice gravitates towards the sunny spot in the living room where she feels most comfortable, while Dave finds himself spending a lot of time at the kitchen table, and Danny (and Danny’s iPhone) put down roots in the office.
Of course, Dave’s personal space also being the kitchen table can cause conflict between Dave’s need for whatever he uses the table for and the rest of the family using the table for cooking and meals. This kind of thing will just need to be negotiated as it comes up.
On the other hand, if Danny is moving into a home that Dave and Denice have lived in for five years, Danny may have trouble finding a spot. Maybe Dave and Denice have put every corner for their home to use. Maybe Danny feels like he’s intruding if they pick a spot as “theirs,” even an other-wise unused spot. Maybe Danny gravitates towards the spot that Denice’s best friend always sits in.
Normally, tis kind of thing will sort itself out naturally. If it doesn’t, then don’t be afraid to sit down together and talk about it.
If one of your poly partners is having trouble finding a spot to be “theirs,” I would consider that a sign that they aren’t feeling comfortable/welcome/at home. Humans are creatures of habit. We like having our own little “nests” to come back to. So if you need a space and haven’t found one, don’t be afraid to talk with your partners about it. It may be a sign of deeper problems in the relationship or it may just mean that you need to rearrange the living room furniture so that one comfy chair catches the afternoon sun.