The statistics may shock you. No one begins a marriage expecting to cheat on their spouse. Vows are exchanged, promises are made and the marriage begins with love and high hopes. What then is the percentage of married couples who cheat?

The Statistics

And yet, according to the Journal of Couple and Relationship Therapy, approximately 50 percent of married women and 60 percent of married men will have an extramarital affair at some time in their marriage. And since it is unlikely that the people having affairs are married to each other in every case, the current statistics on the percentage of married couples who cheat on each other means that someone is having an affair in nearly 80 percent of marriages.  

These numbers represent a huge jump in the past decade. A University of California study in 1998 reported that 24 percent of men and 14 percent of women had had sex outside their marriages. In only 10 years, those numbers have more than doubled.

So why the big increase? Some people blame the huge percentage of married couples who cheat on each other now on the Internet. And research does seem to support this conclusion. According to Divorce magazine, only 46 percent of men believe that online affairs are adultery and 75 percent of married people believe it’s okay to visit an adult site online.

Other sources suggest that:

• 57 percent of people have used the Internet to flirt.

• 38 percent of people have engaged in explicit online sexual conversation.

• 50 percent of people have talked on the phone with someone they first chatted with online.

• 31 percent of people have had an online conversation that has led to in-person sex.

Other interesting facts about infidelity:

• About 10 percent of affairs are one-time and one-day events.

• About 10 percent last more than one day, but less than a month.

• Approximately half of the affairs last more than a month but less than a year.

• The remainder of the affairs lasts longer than a year, with only a very few lasting four or more years.

• Very few affairs end in marriage. According to one large study of businessmen who had affairs, only 3 percent of the men married their lovers.

• According to Peggy Vaughan, author of The Monogamy Myth, most people who have affairs started by age 40, a surprise to the common wisdom which suggests that affairs begin later in life as marriages grow stale.

• Two out of 3 women and 3 out of 4 men admit they have sexual thoughts about people at work, according to Playboy Magazine.

• Most people know when their partners are cheating. Statistics show that 85 percent of women who believe their partners are cheating are correct. Fifty percent of men who believe their partners are cheating are also correct.