From the New York Times :
Married people tend to be healthier than single people. But what happens when a marriage ends?New research shows that when married people become single again, whether by divorce or a spouses death, they experience much more than an emotional loss. Often they suffer a decline in physical health from which they never fully recover, even if they remarry.
And in terms of health, its not better to have married and lost than never to have married at all. Middle-age people who never married have fewer chronic health problems than those who were divorced or widowed.