A year ago my spouse and I got married. 5 years before that, almost to the day, we started dating. I always liked the conincidence of the anniversaries -- having them together like that serves, in my mind,to make them seem more contiguous, as though getting married was another step in the relationship we already had, not something new.
I felt that way before the wedding and looking back on it, a year later, I was right. I suspect its the typical experience of people my age, but moving in together was a bigger change than marriage was, in and of itself (partially because we moved in together with an intention of marrying soon if things worked out). I still count from when we started dating -- not when we got married, so for me the clock stands at 6 years, not 1; to do otherwise seems to disrespect what went before. Maybe in 10 years I'll only mark our years of marriage. For now, I'll have two anniversaries, one day apart.