Suzy Brown, 75, says she tried for “three long, agonizing years” to persuade her husband to break off an affair with somebody he’d met at work. But ultimately, after 33 years of marriage, she filed for divorce.

There’s poor communication, and then there’s harmful communication. The Gottman Institute, which has studied couples’ behavior since the mid-1990s, uses the Four Horsemen of the Apocalypse as a metaphor for the communication styles that, according to the institute’s research, can predict the end of a relationship. The four styles are criticism, contempt (the number one predictor of divorce), defensiveness and stonewalling.

“Contempt severs us from our pack,” institute cofounder Julie Gottman has said. “It leads us to cut ourselves off from others, pull inward and end up alone.”

AARP 5 Reasons Long-Term Marriages End in Divorce