A German study found a man's risk of premature death is 11 percent lower if his wife is seven to nine years younger, perhaps because healthier men attract younger wives. Women with husbands seven to nine years older or younger are 20 percent more likely to die early. [The Telegraph]
Maybe a higher percentage of men who are married to younger women have more money. Thus, they have higher access to better health care which impacts their life span. Just a guess. I really don't know what to say about women's life expectancy decreasing in both directions.