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Why We Fantasize About Other Partners

Some thoughts of straying don't lead to real-world affairs, but others do.

Key points

  • It's possible that people who fantasize about someone other than their partner are simply more likely to fantasize about sex in general.
  • People who fantasize about someone other than their partner may also have fewer inhibitions and feel less constrained by the bonds of commitment.
  • Fantasy infidelities are not a sign that something is profoundly lacking in a relationship, but they can be a gateway to actual infidelity.
Source: oneinchpunch/Shutterstock

In a long-term close relationship, is it inevitable that one or both partners will occasionally be tempted to stray? Perhaps you find yourself inexplicably fantasizing about having a fling with the server at your neighborhood sandwich shop. You know you’d never act on the fantasy, so where’s the harm?

But perhaps this scenario makes you feel uncomfortable. You love your partner deeply and feel that the solid trust you’ve built would become fractured by even the mental indulgence of an infidelity fantasy. And just as anxiety-provoking is the thought of your partner harboring such ideas.

Having a fantasy and acting on it are, the rational mind knows, not at all the same. You’re a grown-up and, unlike your teenage self, you’ve learned to control (most of) your impulsive tendencies. It’s OK to picture having sex with that stranger because you know you’ll never go through with the illicit action. The irrational part of your mind, in contrast, fears that you’re opening a floodgate of desire you won't be able to control.

For the concept of infidelity to exist in a couple, both partners must define the relationship as monogamous. In an open marriage, or among people who practice polyamory, there could, theoretically, be no infidelity. However, in committed two-person relationships, the idea of infidelity is highly relevant.

Infidelity in fantasy can take many forms. In addition to dreams over which you have no control, there is Facebook cheating, in which you may stalk an ex or allow your imagination to run through scenarios with high school sweethearts. You might also catch yourself daydreaming about a fellow student or coworker during a boring meeting or class, or taking a second glance at a stranger on the street who catches your eye. And then there are Hollywood celebrities, the objects of thousands if not millions of fantasies, sexual and otherwise. Do these behaviors constitute infidelity or do they just represent innocent mental escapades?

You can also engage in a more direct form of fantasy infidelity with someone who might pose an actual threat to your loyalty to your partner. People who have "a workplace spouse" may find themselves struggling daily to rid their minds of images in which what has been platonic turns romantic.

Fantasy infidelity may strike at an inconvenient moment. Perhaps you're sharing an actual romantic moment with your partner when that fantasized partner pops up in your mind’s eye. Fighting it off only makes the problem worse, and could ruin the moment.

Among people who actually do cheat on their partners, the causes range from curiosity to the desire for revenge. But infidelity in fantasy is less understood. We might imagine it as an extension of the personality quality of openness to experiencethe willingness to engage in a variety of forms of mental play.

A 2003 study by Spanish psychologists Maria Lameiras Fernández and Yolanda Lameiras Fernández showed that, among undergraduates, at least, those with higher levels of personality openness and lower levels of conscientiousness also had more favorable attitudes toward sexuality in general. Looking at the darker side of sexual fantasies, University of North Texas psychologist Jenny Bivona and her colleagues (2012) reported that female undergraduates who had had "rape fantasies" were also higher in openness to sexual experiences overall.

It’s possible, then, that the people most likely to fantasize about someone other than their partners are simply more likely to fantasize about sex in general. They may also have fewer inhibitions and feel less constrained by the bonds of commitment in a long-term relationship. Even if they never act on the fantasies, they don’t punish themselves for having them.

Whether it’s part of your personality or not, when you have these fantasies, does it mean your relationship is doomed? Are you seeking, as the true unfaithful often do, to make up for a relationship that no longer fulfills your needs? Here again, there is little to guide us from the literature on couples, most of which focuses on actual infidelity.

We do know that relationships evolve over the long term and what was once a passionate love affair with your partner might very well have moderated into a warm and mutually rewarding form of companionate intimacy. Rather than finding a new partner in reality, you use your fantasy infidelities to add some spice to the mix. It’s even possible that you and your partner find it exciting to swap fantasies, including those about other people. In either of these cases, fantasy infidelities are not a sign that something is profoundly lacking in your relationship.

There is a danger, though, that infidelity fantasies become gateway drugs for actual infidelities. This is particularly true if you’re preoccupied with these images and can’t enjoy intimacy with your partner unless your mind is free to go there. In this case, rather than just try to fight back these thoughts, it might be worth trying to examine what might be prompting them.

Is there something about your spouse’s appearance, mannerisms, or behavior in the bedroom (or elsewhere) that is driving you away mentally? If you’re constantly fantasizing about the same person, what qualities does that other individual have that you feel your partner lacks? By allowing yourself to explore your fantasies instead of fighting them off, you may gain insights that you can share with your partner. You don’t need to bring up the fantasies, but you can discuss what they might represent.

Finally, there may be a huge flip side to this as well: People low in sexual desire, whether with their partners or anyone else, may benefit from being encouraged to entertain sexual fantasies.

A team of Italian sexuality researchers, led by Vieri Boncinelli (2013), classified the fantasies of 308 clinical cases of women diagnosed with hypoactive sexual desire disorder. These fantasies weren’t characterized according to the identity of the partner, but to the content of the fantasy itself. The researchers then explored using these fantasies as part of treatment, encouraging the participants to fantasize about their partners. In all but 9 of the 48 cases trying this “fantasy” treatment, the women returned to normal sexual functioning.

If you label your sexual fantasies by their content and not by who they involve, then, it may be possible to view them in a more positive and potentially therapeutic light. You don’t have to succumb to the impulse to act on the fantasy with its original target. Bringing your imagination to bed with you may eventually lead those infidelity fantasies to be replaced by ones that enhance how you and your romantic partner experience shared moments of intimacy.


Bivona, J. M., Critelli, J. W., & Clark, M. J. (2012). Women's rape fantasies: An empirical evaluation of the major explanations. Archives Of Sexual Behavior, 41(5), 1107-1119. doi:10.1007/s10508-012-9934-6

Boncinelli, V., Scaletti, D. G., Nanini, C., Daino, D., & Genazzani, A. R. (2013). Sexual fantasies and female hypoactive desire. Sexologies: European Journal Of Sexology And Sexual Health / Revue Européenne De Sexologie Et De Santé Sexuelle, 22(1), e16-e19. doi:10.1016/j.sexol.2012.08.003

Lameiras Fernández, M., & Lameiras Fernández Y. (2003). The Big Five and sexual attitudes in Spanish students. Social Behavior And Personality, 31(4), 357-362. doi:10.2224/sbp.2003.31.4.357

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