My husband and I had been dating for eight long years before we got married and we never lived together ... (mainly because I was in high school then went to college
) I sometimes wish that we had because it was like getting used to each other all over again when you've been accustomed to doing things your own way. After three years I think we're finally starting to get the hang of it!
My advice would be to make sure you have a plunger in every bathroom.