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5 Insights on How Dark Personalities See Infidelity

Different views of whether fantasizing equals infidelity.

Key points

  • New research examines the views of people with Dark Triad personality traits regarding infidelity.
  • Research shows that Machiavellians rarely consider fantasizing about someone or forming intimate emotional bonds with strangers as unfaithful.
  • Psychopaths, in contrast, tend to view emotional bonds and fantasizing, but not sexual acts, as infidelity.

A recent study by Brewer et al., published in Personality and Individual Differences, suggests there are five types of infidelity, and that personality traits—specifically, Dark Triad traits—predict which of these acts are perceived as cheating.

The Dark Triad

The Dark Triad consists of three personality traits associated with manipulative and exploitative tendencies:

  1. Machiavellians. People high on Machiavellianism are cold, cynical, and calculating.
  2. Psychopaths. Individuals high on psychopathy are callous and ruthless but superficially charming.
  3. Narcissists. Those high on narcissism tend to feel superior, entitled, self-important, and often jealous.

Note: Sometimes sadism is added to the list of the Dark Triad, forming the Dark Tetrad. Sadists, simply put, enjoy causing others suffering. For instance, individuals who meddle and interfere in the relationships of friends and family may have sadistic tendencies.

What people with Dark Triad traits have in common is being manipulative, overvaluing themselves, devaluing others, and creating “justifications” for their views.

To illustrate, a narcissist may reason, “I deserve special treatment because I am more attractive, intelligent, and popular than others. People who disagree are either too stupid to see my superiority or too jealous to admit it.”

The study by Brewer and coauthors examined what unfaithfulness means to individuals with Dark Triad personality traits.

Investigating how Dark Triad personalities view infidelity

Sample: 676 people (436 women); age range of 18 to 73 years (average of 30 years old), 72% heterosexual and 22% bisexual.


  • Mach IV: Twenty items measuring Machiavellianism (e.g., “Anyone who completely trusts anyone else is asking for trouble”).
  • NPI-16: Sixteen statement pairs measuring narcissism. For example, “I like to be the center of attention.”
  • Levenson Self-Report Psychopathy Scale: Twenty-six statements assessing psychopathy, such as, “For me, what’s right is whatever I can get away with.”
  • Perceived Infidelity Questionnaire: Twenty-one items. Participants were asked whether specific acts—such as having intimate phone conversations with strangers—should be considered cheating.

The Dark Triad and 5 types of unfaithfulness

The research identified five types of infidelity: Emotional infidelity, fantasized infidelity, sexual infidelity, online infidelity, and hidden attachment (i.e. secret feelings of attraction).

Analysis of data showed the Dark Triad personality traits of Machiavellianism and psychopathy “predicted the extent to which specific acts were perceived to constitute infidelity.” Namely, Machiavellians did not consider fantasizing an act of infidelity. Why? Remember that Machiavellians are long-term strategists; their romantic relationships tend to be characterized by manipulation and exploitation. Hence, unless a partner’s fantasy interferes with their strategic goals of status or control in the relationship, Machiavellians might not worry about, say, erotic daydreams. Neither were they, according to the data, inclined to see expressed emotion as infidelity. This makes intuitive sense because Machiavellians dislike intimacy; therefore, learning that their mate has formed an emotional bond with another person does not worry them either.

The results showed that psychopaths, in contrast, viewed emotional expression and sexual fantasies as infidelity. This may be due to their keen sensitivity to infidelity and strong tendency to experience jealousy. A second potential explanation is that due to a lack of empathy and deficiencies in perspective-taking, a psychopath may find it difficult to understand why his or her husband/wife engages in sexual fantasizing or has formed emotional attachments to others. In other words, psychopaths cannot distinguish these behaviors from more blatant acts of infidelity.

Surprisingly, psychopaths were less inclined to “consider sexual acts or hidden attachment as indicators of infidelity.” Why? Psychopaths are more likely than others to commit sexual infidelity themselves; so, by saying sex outside the relationship is not cheating, they may be attempting to justify their own unfaithfulness and extramarital affairs.


New research identified five categories of infidelity:

  1. Online infidelity. These included behaviors with clear sexual intentions but also ones with unspecified intentions (e.g., receiving pictures from a stranger).
  2. Fantasized infidelity. Solitary sexual behavior, such as erotic fantasizing about a friend.
  3. Emotional infidelity. Having an emotional bond with a stranger.
  4. Sexual infidelity. Engaging in sexual behaviors with a person other than the partner.
  5. Hidden attachment. Unexpressed/unfulfilled feelings of attraction to another individual.

Dark Triad personality traits correlated with the extent to which particular acts were seen as infidelity.

  • Machiavellians were less likely to consider emotional bonding or sexual fantasizing as cheating.
  • Psychopaths showed a greater inclination toward categorizing emotional attachment and fantasizing as cheating but less inclination toward doing so for hidden attachments and actual sexual behaviors.

(Note: There was no clear relationship between narcissistic tendencies and perceptions of infidelity.)

Individuals with Dark Triad personality traits are, by definition, manipulative, so it is not surprising that they seek particular types of sexual and romantic relationships (e.g., psychopaths’ preference for one-night stands) or have unique views of infidelity.

By learning more about how Dark Triad individuals use their partners to pursue hidden agendas (e.g., obtain money, status, control, admiration), we can become better at preventing being taken advantage of and manipulated by them. Knowing their views on what it means to be unfaithful is a first step in that direction.

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