People create hormones such as prolactin when they sleep. Prolactin is made during pregnancy, during breastfeeding, while falling in love, while making love and is higher in people who are in love. People throw this hormone off during sleep, when they are sleeping with someone they love and it appears that their partner can somehow sense this hormone (maybe it is also a pheromone, but not enough research has been done) and this may be part of what works to strengthen the relationship and the closeness of the couple.
We always sleep in the same bed. Once in a while he may fall asleep on the floor or couch in the living room, but he always comes to me long before dawn. Years ago, I used to start the night in my toddler's bed, as she was still breastfeeding and needed the same prolactin for her to not only be able to sleep, but to bond well with me. I would then, after she was deeply asleep, go to bed with my husband.
My husband's parents had separate rooms for decades. My Man doesn't talk about it in detail but I know it bothered him a lot. I mentioned it a few times and he said, "That will never be us!" I know they had pretty severe sexual issues, but I don't know the details (and I don't want to know them.)
The occasion night away from one's love is understandable, work, a convention or business trip, even an illness may separate us for a night or two, but we always rejoin each other in our bed.
Everyone has a different relationship and a different type of bonding. It works for us, but I can't speak for everyone.
Mileage and all that.
