Marriage confers benefits that go beyond what partners bring into the marriage. It's not just that healthier or more responsible people marry and, therefore, married people are healthier and more responsible. It's that being married changes people for the better. For example, couples can benefit from strong social support. Knowing there will be someone in your corner who will be interested in the details of your life can lessen stress levels substantially.
Couples also can benefit from bouncing ideas off each other or talking through issues and concerns.
They have a support system, ready and waiting. In a marriage, each partner has a stake in the relationship and its success. It matters if a partner neglects his or her health, suffers through turmoil at work or struggles with a career change. Couples are less likely to smoke or drink to excess. They also are more likely to schedule regular check-ups and follow through on exercise or other recommendations that will improve their lifes or health.