"Men's affairs in particular are often the cause of troubled marriages and not the effect. In my data, 56 percent of men who entered into affairs said they had ''happy'' or ''very happy'' marriages, compared with 30 percent of women. For men, the strongest predictor for having an affair is their attitudes and values about monogamy. For women, it's marital unhappiness."
--Author and psychotherapist Shirley Glass, in her book NOT Just Friends