Story highlights A third of married women who have sex outside their relationships describe those marriages as "happy" or "very happy"

Women's bodies respond to a wider variety of sexual stimuli than do men's

(CNN) Women are more faithful than men. Women cheat for love; men cheat for sex. Women are less sexually adventurous than men. It's a script that many of us -- whether clinicians or Hollywood -- follow when thinking about female sexuality. Yet it's a script based on unfounded assumptions about the way women view, pursue and engage in sex, writes Wednesday Martin, author of "Untrue," in which she mined the data and interviewed 30 experts and women from all walks of life to uncover the facts about female sexuality.

In her book, Martin addresses some of the most common myths and misconceptions about women and sex.

Myth: Women cheat for 'emotional' reasons.

When women are unfaithful, it's easy to assume that they cheat out of dissatisfaction with their relationship, because they fall in love with someone else or because they're looking for a way to end their marriage.

"I'm convinced that we believe this because we presume it, and then socialize other people to believe it," Martin said. "But peel back the language, pay attention to the storytelling and the data, and you'll hear similar things from both sexes: Infidelity is exciting and gratifying for many men and women, emotionally and physically."

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