My wife was always the saver, from a young age, and I was the one in loads of debt when we got married. I moved out at 17, with no high school diploma, working at MCDonald's, and no concept of money at all.
Over the years since, I've become our finance expert, managing all the money, and keeping our spending in check. My wife has zero interest in managing money, finding deals, cutting costs, etc, but she is happy that I do, and is happy to go along with whatever.
So we're lucky to be very in sync with our spending and savings habits, we never argue about money.
I see other couples, family and friends, who have large differences in their approaches to finances, and it causes them endless problems. One spender and one saver is a bad combo for a relationship.