It is estimated that roughly 30% to 60% of all married individuals (in the United States) will engage in infidelity at some point during their marriage (see Buss & Shackelford for review of this research).
https://www.truthaboutdeception.com/cheating-and-infidelity/stats-about-infidelity.html
The research, which looked at 100 heterosexual, married females between the ages of 35 and 45 and their online conversations with potential suitors on discreet dating service AshleyMadison.com, found that 67 percent of the women seeking an affair cited the desire for more passion.
http://www.huffingtonpost.com/knowmore-tv/why-happily-married-women-are-cheating_b_5787280.html
Why Happily Married Women Are Cheating. If you're under the impression that it's mostly men who cheat on their wives, then you are mistaken. According to new research, many married women are seeking affairs for romance and sexual satisfaction without any plans of divorcing their partner.
http://www.huffingtonpost.com/knowmore-tv/why-happily-married-women-are-cheating_b_5787280.html
Now, the unfortunate exception: Some do. Okay, a lot Do: The incidence of extramarital intercourse for women is 25 percent, and the estimate of single women who've cheated is even higher. And if a woman is going to cheat, there are surprisingly specific times when she's likely to do it.
http://www.menshealth.com/sex-women/6-signs-shes-thinking-cheating
Anderson also reasoned that women only have affairs with one man because of the need to feel emotionally connected in order to be satisfied sexually. Men, on the other hand, tend to cheat with many women. There's less risk of exposure when emotional connection doesn't come into play, according to Dr. Greer.
http://www.huffingtonpost.com/knowmore-tv/why-happily-married-women-are-cheating_b_5787280.html
Up until two hundred years ago, couples generally married for proof of genetic monogamy, in order to pass down their sheep or their farmland. This monogamy was necessary to ensure that no one cheated outside of the family lines and that property ownership stayed within the male lineage.
http://www.independent.co.uk/life-style/love-sex/are-we-meant-to-be-monogamous-why-people-cheat-open-relationships-and-life-after-an-affair-10097811.html
Also, women with fat salaries are more likely to cheat. A University of Washington study found that people who earned $75,000 or more per year were 1.5 times more likely to have had extramarital sex than those earning less than $30,000.
http://www.menshealth.com/sex-women/6-signs-shes-thinking-cheating
Facts and Statistics About Infidelity. Given the secretive nature of infidelity, exact figures about cheating and extra-marital affairs are nearly impossible to establish. But listed below are some of the most well-supported facts about cheating. All cited sources can be found on our reference page.
https://www.truthaboutdeception.com/cheating-and-infidelity/stats-about-infidelity.html
By Nicola Gallagher for KnowMore.tv. If you're under the impression that it's mostly men who cheat on their wives, then you are mistaken. According to new research, many married women are seeking affairs for romance and sexual satisfaction without any plans of divorcing their partner.
http://www.huffingtonpost.com/knowmore-tv/why-happily-married-women-are-cheating_b_5787280.html
The plan: If you are cheating or have cheated before, confess and apologize. A survey conducted by Peggy Vaughan, author of The Monogamy Myth, showed that 86 percent of couples who discussed one partner's affair were still married, compared with 59 percent of couples who barely talked about it. If you're not cheating, you have one paranoid woman on your hands.
http://www.menshealth.com/sex-women/6-signs-shes-thinking-cheating
what percent of married women have affairs
There are 67 percent of married women have affairs. About 67 percentage of married women has an affair.  There are 25 percent of married women who have affairs. There are 25 percent of married women have affairs.