RubyToogood
RubyTwobikes
Although actually if you dig around a bit there are some very critical articles of the studies that appear to show single people (especially men) don't live as long. This is a cheering read on both longevity and happiness.
Plus there's the issue that it can be a person's health that impacts the likelihood of them coupling up as well as their longevity, rather than that their relationship status impacts their health necessarily.A review of 18 such studies found that people generally become no happier after they get married. At best, they become a bit more satisfied with their lives around the time of the wedding; then they go back to feeling about as satisfied (or dissatisfied) as they were when they were single.