When it comes to happiness, what's love got to do with it?

When it comes to happiness, what's love got to do with it?
How accurate was William Shakespeare when he said, "'Tis better to have loved and lost than never to have loved at all"? Researchers from Michigan State University conducted one of the first studies of its kind to quantify the happiness of married, formerly married and single people at the end of their lives to find out just how much love and marriage played into overall well-being.