The best part of moving-in with a spouse or person you're dating is getting to play "Let's try to diagnose the mental disorder." A game that you can't play when you're merely dating someone there isn't enough time together in a person's habitat. Don't worry single people can play it too, provided they have roommates. The more roommates the more hours of enjoyment you can spend google searching symptoms like: "Chronic key loss," "Dish cleaning phobia," "Enjoys starting home improvement projects he'll never finish," or "Randomly screams alone in the middle of the night." Then you get to read the diagnosis on Web MD: "Adult ADD/ disorganization disorder," "You're roommate probably did grow up in barn without running water or plates, " or "Paranoid Schizophrenic."
The game is so fun I think that's why Mormons are into polygamy.