sides of the bed? A very common thing with most couples I know and in my experience. I mean- I don’t know any couples that treat it like two sovereign nations where your partner can’t “intrude” over the border or use the entire bed or any part of the bed while you aren’t in it etc-
But most people (I know of) tend to prefer one side of the bed or the other to sleep on and most couples I know tend to negotiate that.
Then when you factor in your stuff-
So for example you might have a firm pillow and your partner has a soft pillow, and it is common to have night stands and keep your things- maybe some lotion, sleep mask, hair bonnet, or other personal items you use before bed, your book, specific chargers for your devices…
And it is a bit of trouble to relocate all that stuff on a whim- especially if your partner decides to fall asleep first on the side of the bed that has all your things. What are you going to do, unplug and move your things quietly while they sleep? It just is a bit odd isn’t it, like- your Parker uses two pillows with a silk case and they are on the left side of the bed, they have an android and you have an iPhone- so they move your single pillow with Jersey tee case to the right, move their two pillows to the left, and then plug their phone in next to where you’ll sleep and/or reach the cord across so they can fall asleep looking at their phone and there’s a cord across the martes where you sleep…?
And that’s before special cases. I used to get up at 4am but my partner didn’t need to be up until 8. I had an alarm clock with a little “puck” that vibrated and would wake me up at 4 but not her. It was slightly elaborate to set up and was all wired. Anyone with anything like that- it wouldn’t make much sense to switch sides of the bed with any regularity. Likewise some people have things like “sleep number” beds and while you could just change both sets of numbers, that seems to be a bit of extra trouble for what? To switch sides of a bed? I mean at the end of the day even in relationships where people have “their side” of the bed it is generally “our bed,” as said early, I don’t know anyone who does it like a feuding sitcom family or petty siblings and is going to get all bent up of you cross some imaginary line.
It’s more a case of “I’m going to put my stuff on this side and make this side comfortable for me and you’re going to put your stuff on that side..” likewise placement can matter. I’ve had parters or known people who like the bed close to a wall and feel more secure sleeping next to the wall, then I’ve known people who prefer not to climb over the bed or like the feeling of freedom not being near the wall. If a bed is near a wall on one side, one partner might use the bathroom more during the night or get up to get water etc. so it might be prudent for them to sleep on the “open side.” Likewise if one partner usually goes to bed later or wakes up earlier having them on the “open side” can mean that the other partner doesn’t need climbed over and is likely going to give them a better chance at I disturbed sleep.
I’ve known people who like the side of a bed closer to a door because they want to see out of the room or feel safer near and exit and I’ve known people who like further from the door because they feel safer away from the entry way were someone to barge in. I know people who like sleeping closer to a window because they get how or like the view and people who like being away from a window as they get cold or the noise can bother them or they feel vulnerable. Some people like to sleep “face to face” as opposed to spooning- if you like sleeping face to face but are a right side sleeper, your partner needs to be to your right and sleep on their left side because of they are to your right you either would spoon if they sleep right side or face away if they sleep left. If you are both right side sleepers and like to spoon, the side you each occupy will determine who is “little” and “big” spoon.
So I mean- between two people sharing a bed whatever system works for them is fine. Using an above example, if you both want to sleep your right side but you like to alternate big and little spoon then you may need to swap sides to make that happen. And of course if you both have identical pillows and cases and such then it may not matter or if you don’t notice things like the specific indentation your natural sleeping places into pillows or mattresses then those aren’t issues either. You might not keep your phones near the bed or in the bedroom. You might not have nightstands at all or some people have identical amenities on their nightstands. So to each their own. It’s all about what works for the two people sharing that space. Though just for the record the “sides” thing is common in my experience and it can still be “our bed” and people can have sides.
But most people (I know of) tend to prefer one side of the bed or the other to sleep on and most couples I know tend to negotiate that.
Then when you factor in your stuff-
So for example you might have a firm pillow and your partner has a soft pillow, and it is common to have night stands and keep your things- maybe some lotion, sleep mask, hair bonnet, or other personal items you use before bed, your book, specific chargers for your devices…