Healthy relationships have been linked to longer lifespans. According to Dan Buettner, committing to a life partner can add 3 years to life expectancy.
People with strong relationships are more likely to have better health. According to research conducted by Sheldon Cohel, college students with stong relationships are 1/2 as lifely to catch a common cold when exposed to the virus.
Lower risk of depression. Several studies have shown that people with stronger relationships tend to have lower risk for depression.