I believe it's important to "trial" all aspects of a relationship before marriage (don't I sound cold-hearted!
). Afterall, the sex may be wonderful, but what if your spouse has questionnable personal habits, can't hold down a job, is a secret drinker, is a slob around the house ... or perhaps you are? Personally, I'd much rather discover my partner's true nature before signing on the dotted line. Let's face it, the sex is always "amazing" at first (or we're so high on love we manage to convince ourselves it is). Sex plays an important part in marriage, but there's so much more to a relationship than that ... isn't there? Will your spouse be able to offer you the cuddles and emotional support you need? Will you be able to, or want to, give to them emotionally?
You can't really know someone until you share a home with them; until you see them (and they you) in all your glory.
My husband and I lived together for four years before we married. And yes, I was aware before we married that he is completely unable to put dirty clothes in a laundry basket, that his movement through a room leaves a trail of destruction behind, but balanced against all the other wonderful things about him ... I can live with it, but better to know BEFORE you make it official!