If anything living with that person teaches you about your temperament. Having someone stay over 3 times a week is different than someone in your face 24/7, barging into the bathroom when you trying to take a dump, pets, how clean that person is, etc. This is a buyer's market. It would be silly not to take advantage of it.
That's why you communicate with your spouse. "I don't like it when you..." Marriage isn't supposed to be easy with you having covered every scenario possible before you do it for real. Even if we compare it with a test drive, the car could still break down after you get it home.