Sometimes I worry that society is becoming immune to infidelity and cheating in a romantic relationship. We hear things like, “Half of all marriages end in divorce” and “Half of people in a relationship admit to cheating.” We become desensitized and perhaps a bit pessimistic by hearing these disheartening statistics repeated over and over again.

It’s become so bad that some people are even making up statistics to either sell their infidelity-helping or infidelity-fighting services. For instance, one common statistic I hear thrown out there is that 50 percent of relationships involve infidelity.

Sadly, that statistic is not based upon any scientific research. It’s something marketing companies just made up and use to scare (or motivate) people into buying into their service.

So how common is cheating, really?

The short answer is, “Not nearly as common as you would be led to believe.”

I last talked about infidelity a few years ago, and why people cheat. But what I didn’t cover is exactly how common — or, to put it more accurately, uncommon — cheating actually is.

The Prevalence of Infidelity

Researchers Blow & Hartnett (2005) ((Sorry, I am not making their names up.)) took a comprehensive look at this issue and reviewed all the research on infidelity a few years ago. Here is what they have to say about how common cheating really is:

Many research studies attempt to estimate exactly how many people engage in infidelity, and the statistics appear reliable when studies focus on sexual intercourse, deal with heterosexual couples, and draw from large, representative, national samples. From the 1994 General Social Survey of 884 men and 1288 women, 78% of men and 88% of women denied ever having extramarital (EM) sex (Wiederman, 1997). The 1991-1996 General Social Surveys report similar data; in those years 13% of respondents admitted to having had EM sex (Atkins, Baucom, & Jacobson, 2001).

In the 1981 National Survey of Women, 10% of the overall sample had a secondary sex partner. Married women were the least likely (4%), dating women more likely (18%), and cohabiting women most likely (20%) to have had a secondary sex partner (Forste & Tanfer, 1996). […]

Compared with Laumann et al. (1994), other authors report significantly lower prevalence statistics. General Social Surveys conducted in 1988 and 1989 showed that a mere 1.5% of married people reported having had a sexual partner other than their spouse in the year before the survey (Smith, 1991), and less than 3% of Choi, Catania, and Dolcini’s (1994) sample had engaged in EM sex in the previous 12 months.

In a 1993 probability sample that included 1194 married adults, 1.2% had EM sex in the last 30 days, 3.6% had EM sex in the last year, and 6.4% had EM sex in the last 5 years (Leigh, Temple, & Trocki, 1993). These results possibly indicate that the number of EM sexual involvements in any given year is quite low, but that over the lifetime of a relationship this number is notably higher.

In general, based on the above data, we can conclude that over the course of married, heterosexual relationships in the United States, EM sex occurs in less than 25% of committed relationships, and more men than women appear to be engaging in infidelity (Laumann et al., 1994; Wiederman, 1997). Further, these rates are significantly lower in any given year. […] (Blow & Hartnett, 2005)

Another study conducted on a population-based sample of married women (N = 4,884) found that the annual prevalence of infidelity was much smaller on the basis of the face-to-face interview (1.08%) than on the computer-assisted self-interview (6.13%) (Whisman & Snyder, 2007). ((This intriguingly suggests people are more comfortable telling the truth to a faceless computer survey than to a human interviewer.))

Taken together, in any given year, it looks like the actual likelihood of your relationship suffering from cheating is low — probably less than a 6 percent chance.

But over the course of your entire relationship, the chances of infidelity may rise to as much as 25 percent. Twenty-five percent — over the course of an entire relationship — is a far cry from the 50 percent number we hear from many so-called professionals and services trying to sell you something.

And to put cheating into perspective too, the relationship (or one of the people in the relationship) needs to be lacking in something. As my previous article on the topic noted, these risk factors typically include: significant, ongoing, unresolved problems in the primary, long-term relationship or marriage; a significant difference in sex drive between the two partners; the older the primary relationship; a greater difference in personality than perhaps the partners realize; and having been sexually abused as a child.

Whisman & Snyder (2007) also found support that the likelihood of infidelity decreases the more religious you are, as you age, or if you’re better educated. They also found that the risk for cheating was greater for women who were remarried (compared to those who were on their first marriage), or for either gender with the greater number of sexual partners you have.

Types of Infidelity

Cheating comes in many different forms — it’s not limited to simply having sex with someone who isn’t your long-term partner.

Both the clinical and self-help literature reference general types of infidelity, including one-night stands, emotional connections, long-term relationships, and philandering (Brown, 2001; Pittman, 1989). However, most of the empirical literature does not delineate these types of infidelity, nor does it offer ideas on how prevalent different types of infidelity are or in what kinds of relationships they exist. […]

There is evidence that there are emotional-only, sexual-only, and combined sexual and emotional types of infidelity (Glass & Wright, 1985; Thompson, 1984). These categories are not necessarily mutually exclusive, and Glass and Wright (1985) explore infidelity on a continuum of sexual involvement and emotional involvement.

Further, within each general category there are different types. For example, emotional infidelity could consist of an internet relationship, a work relationship, or a long-distance phone relationship. Sexual infidelity could consist of visits with sex workers, same-sex encounters, and different types of sexual activities. (Blow & Hartnett, 2005)

Cheating is something to be aware of in any relationship. However, in most relationships, it is not something to be overly concerned about unless you have one of the above risk factors. Even then, the rate is half as what many marketers would have you believe — and that’s some good news for a change.