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3 Different Kinds of Infidelity

And how they matter when you decide how to move on.

Kat Jayne/Pexels
Source: Kat Jayne/Pexels

If your partner cheated on you, at least you are in good company. It is estimated that cheating occurs in 25 percent of committed—or at least, supposedly committed relationships. The estimate is almost certainly an underestimate. How many people, when surveyed, are going to admit that they have cheated or, worse, are cheating now?

There are three main kinds of infidelity, and further subdivisions exist as well. Before figuring out how to react to infidelity, it helps to identify the kind.

Sexual Infidelity

Sexual infidelity may seem to some to be black-and-white. Either they &%*@$! or they didn’t! But where is the line? Kissing? Petting? Oral sex? Something else? And was that kiss the proverbial peck on the cheek or a deep French kiss? Does it matter?

Even if they are having sex, you need to know why. Consider a taxonomy. It is only one of many, all of which overlap.

Serial Philanderers

Philanderers are continuously on the look-out. They are opportunistic. The philanderer is always checking out opportunities for sex. It does not matter whether it is at work, while having fun, or combining work with pleasure.

Serial philanderers are collectors: They collect partners the way other people might collect artworks or coins. Love stories, such as the “collector story,” are hard to change, despite promises, New Year’s resolutions, and even painful penalties like a string of past failed relationships. If you are with a philanderer, either get used to it or get out. Your partner likely won’t change.

Asking your partner whether he or she is shopping around is not likely to succeed. There are some signs of serial philanderers that tend to be pretty reliable. They may be away a lot and have shifty or changing explanations. They may seem to come alive from the dead when an attractive person enters their space. They may keep having to “work late.”

Often, any of us can be the last person to learn we are with a philanderer. Ask around; other people likely know, even if you don’t!

An extreme form of a serial philanderer is the conqueror. He (it could be a she, but usually it’s a he) is looking to make conquests. If you are with one of them, forget it. Once the conquest is made, you’re history.

Incidental Active One-Night Standers

An incidental active one-night stander will actively take advantage of an opportunity for a one-night stand. Maybe they were at a party. Maybe everyone was drunk or high. Maybe the business dinner went beyond business, or at least, the original business. These partners will take advantage of opportunities as they prevent themselves, but will not constantly be on the look-out, like the serial philanderers.

Incidental Passive One-Night Standers

These people do not look for sex but do not always resist the opportunity when someone presents it to them. They may put up passive resistance, but it gives way without superhuman effort on the part of the aggressor. These people are up for a one-night stand, but not actively looking for it.


Avengers are pissed off. Their main preoccupation is not necessarily the affair, but to even the score—one way or another. People usually want equity in their relationships—they want to get back from their partner roughly in proportion to what they give the partner. The infidelity may be revenge for the other partner’s having an affair, but it may be a way of evening the score for an argument, for real or imagined abuse, or for feeling that they deserve much more than they are getting from the relationship.


Long-termers are in it for the long-term; except that “it” does not involve you. The long-termers are getting something out of an alternate long-term relationship. Whatever it is, they don’t think you provide it.

Why do people get into long-term infidelity? They may feel that their primary relationship is lost, but not want to get a divorce for reasons of children, religion, or money. Or long-termers may see themselves as polyamorous—as believing it’s OK to love multiple people intimately, more or less all at once.

From their point of view, they get different things from each partner. They may not even view the additional partner as a threat to the primary relationship. Their partner in the primary relationship, however, may beg to differ.


Victims are forced into sex and are given no choice or opportunity to refuse. They may have tried to resist, or they may have been too scared to resist. Either way, victims did not give voluntary consent to sex. Obviously, they need support, not blame or shame.

Emotional and cognitive infidelity

Emotional infidelity may or may not involve sex. It occurs when a person has intense feelings for a third person. It may be short- or long-term. It is a threat when the third party displaces the primary partner in one’s feelings and perhaps one’s dreams of the future.

It does not require physical meetings. It can and often does occur over the Internet, telephone, or snail mail. The problem with emotional infidelity in a relationship is that when your partner is there with you, they are not there for you.

Emotional infidelity is often accompanied by cognitive infidelity—when someone is thinking a lot about and may even be obsessed with someone else. Their thoughts are with a third person.

Take-Home Message

Sooner or later, opportunities for infidelity like will arise. You should discuss with your partner early in the relationship what you each mean by ”infidelity.” Can you reach an agreement? Can you talk to your partner when your relationship is threatened? The best way to head off problems in the future is to prepare for them before they happen.


Blow, A. J., & Hartnett, K. (2007). Infidelity in committed relationships II: A substantive review. Journal of Marital and Family Therapy,…

Equity: Overview of equity theory.

Sternberg, R. J. (2020). What is infidelity anyway?

Sternberg, R. J. (2019). Love stories.…