At least according to Dr Roizen, it does."One of the best social supports can be your marriage, and that fact is reflected in our health and longevity. Happily married couples live longer. Although there are few data on unmarried people who are in long-term, mutually monogamous relationships, we may assume that the same is true for them, too. Indeed, people who indicate that they are happily married show a RealAge (physiologic age) difference of as much as 6.5 years younger than their unmarried counterparts..."
Dr Roizen focus his research on anti-aging. You can read his bookThe Real Age Makeover -take 10 years off your looks and add them to your life