The Four Horsemen of the Apocalypse predict an ailing marriage: Criticism, Defensiveness, Stonewalling and Contempt. The worst of these is contempt.
John M. GottmanWhen a couple gets to the last stage, one or both partners may have an affair. But an affair is usually a symptom of a dying marriage, not the cause. The end of that marriage could have been predicted long before either spouse strayed.
John M. Gottman