Scott Rick (Wharton), Deborah A. Small (Wharton) and Eli Finkel (Northwestern) report:

Although much research finds that "birds of a feather flock together," surveys of married adults suggest that opposites attract when it comes to emotional reactions toward spending. That is, "tightwads," who generally spend less than they would ideally like to spend, and "spendthrifts," who generally spend more than they would ideally like to spend, tend to marry each other, consistent with the notion that people are attracted to mates who possess characteristics dissimilar to those they deplore in themselves (Klohnen and Mendelsohn 1998). In spite of this complementary attraction, spendthrift/tightwad differences within a marriage predict conflict over finances, which in turn predict diminished marital well-being. These findings underscore the importance of studying the relationships between money, consumption, and happiness at an interpersonal level.

Thanks to Marginal Revolution