When alone, I sleep on the right side - that is, if I'm on my back, my right arm is next to the edge of the bed and there's "space" next to my left arm. That space is generally occupied by one or both of the dogs. Cats wedge in wherever there's room left, one of them usually between my ankles. The big dog generally "drifts" closer and closer, so if the not-quite-as-big dog has to go out in the middle of the night, I have to either get back in on the other side or make the big sleeping-like-a brick hunk of dog move - no easy task, I tell you.
The most recent man I shared my bed with slept where I generally do when alone, and I slept to his left. The dogs stayed in the living room - they figured that out on their own.
The previous guy slept to my left. No dogs at the time.
When I was married, my husband slept to my right. It was a different room in a different house, and a different bed. No dogs, cats at the foot. (Different cats, too.)
campfire