Researchers at Iowa State University and Purdue discovered that married couples are more likely to divorce if a wife gets sick, compared to when a wife remains healthy.  However, they were not able to determine who initiates the divorce.

The study, published in the Journal of Health and Social Behavior, determined that a married couple was 6 percent more likely to divorce if the wife is sick, while a husband's illness did not increase the likelihood of divorce.

For the study, researchers tracked the onset of serious illnesses such as cancer, heart problems, lung disease or stroke.  They found that in 2,701 marriages, using the Health and Retirement Study (1992-2010) revealed that illness' impact relationships heavily by leading either to divorce or widowhood.

They found that a wife's illness onset was associated with an increased risk of divorce, while a husband's was not.  "These findings suggest the importance of health as a determinant of marital dissolution in later life via both biological and gendered social pathways," the researchers say.

"There is a difference between feeling too sick to make dinner and needing someone to actually feed you," she said. "That's something that can really change the dynamics within a marriage. If your spouse is too sick to work, we know that financial strain is a major predictor of divorce in and of itself," said Amelia Karraker, lead author and assistant professor of human development and family studies at Iowa State.

While many may assume that the divorce is initiated by the men, the study failed to identify who initiates the divorce.  Karraker noted wives are "generally less satisfied" with care from husbands meaning it is possible that women are seeking the divorce, rather than the men.

In the study, 32 percent ended in divorce, 24 percent in widowhood.  Researchers also found that divorce was more common in younger spouses while widowhood was more common as respondents age.

Mary A Languirand, a clinical psychologist, warns that couples in caregiving should see a therapist.  "Caregiving can be extremely stressful, so much so that full-time caregivers are actually at increased risk for depression, health problems and substance abuse. It can cause relationship conflict as well (especially when one member of a relationship feels neglected)," Languirand says.

Karakker initially conducted the research while at the University of Michigan presenting the results the Population Association of America's annual meeting.  She said her interest in the subject was originally sparked by the criticism received by both John Edwards and New Gingrich when they divorced their sick wives.