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. They may do so as a team or simply provide each other the reminder what's needed to see that the follow through occurs.
Couples enjoy economic benefits, too.
The possibility of two incomes can buffer job and other stresses and make a more comfortable lifestyle a reality. Undertaking family life as a couple can contribute to a couple's sense of well being and benefit the family. Children who are raised in a two-parent home where parenting responsibilities are shared usually fare better in life. The couple and their family also can benefit from a larger social circle. Their circle of family and friends is wider, so their opportunities are likely to increase.