It’s known as the widowhood effect, considered by social scientists to be “one of the best documented examples of the effect of social relations on health,” as Nicholas A. Christakis of Harvard and Felix Elwert of the University of Wisconsin–Madison wrote in 2008, in what is perhaps the best existing study on the subject. Previously, as Christakis and Elwert note in their paper, research suggested that within the three months after one spouse dies, the chance that the other will follow is anywhere from 30 to 90 percent.

For their study, they went big — it’s the largest and most comprehensive research project to date on the phenomenon. Christakis and Elwert analyzed nine years’ worth of data collected from nearly 373,189 elderly married couples in the U.S., specifically looking at when each half of the pair died, and why. Their findings showed an 18 percent increase in “all-cause mortality” for men whose wives died first; for women, the risk is 16 percent. “The death of a spouse, for whatever reason, is a significant threat to health and poses a substantial risk of death by whatever cause,” they conclude.

The question, then, is why. In cases like the Fluties’, the quick death immediately following bereavement may be caused by the intense physical ramifications of grief. “The No. 1 cause of death of a bereaved spouse is heart disease and sudden death, meaning the heart stops,” reported NBCNews.com, quoting internist Dr. Lee Lipsenthal. (Lipsenthal has since passed away himself.) It’s been called “broken heart syndrome,” the colloquial term for takotsubo cardiomyopathy. “The condition nearly always follows a traumatic emotional loss, such as death of a spouse, parent or child and it primarily affects women,” wrote NBCNews.com reporter Linda Dahlstrom, referencing Cleveland Clinic geriatric specialist Dr. Barbara Messinger-Rapport. “It causes chest pain and sudden heart failure, believed to be brought on by a surge of fight or flight hormones.”