Marriage, Partnership and Sleep - Good for Men, But . . .
Married (partnered) women report poorer sleep than married men (until they get old). Us blokes conk out like a light, while our noises and tossing keeps our female spouse awake. The article and research makes no comments about same-sex partnerships, so I can only speculate. Despite my wry summary, the reasons are undoubtedly complex, and different for different people.
There’s a great deal of social convention about partnerships and sleeping arrangements. But really, if you’re not sleeping well when with your partner, there is no reason to persevere with that sleeping arrangement. Take to the spare room if it helps. You can cuddle first (and have sex even), but if a separate bed helps you sleep then go there. Your overall quality of life and your relationship will benefit from having good sleep, and if your relationship cannot cope with such a slight compromise as separate beds then you’re probably doomed anyway so get it over with and get a good night’s sleep.
Article on the sleep quality of married folk.
There is also evidence that sleep and relationship issues may affect men and women differently. If a man sleeps well his interactions the next day will be better and more harmonious. In other words, lack of sleep will make him grumpy the next day. Women report that it works the other way for them, as a generalisation. If they have a tetchy day with their partner it keeps them awake that night. More here.