Married people are happier. And there is a lot of evidence that depression is a risk factor. It makes sense that if you are generally happy in life, that would be both a cause and an effect to a longer life.
People in the United States, on average, marry in their mid to late 20s, and half of all divorces take place in the first seven years of marriage.
It brings people into the building. That's the whole idea ... that people will know that something interesting is happening here.