An article from Norwegian SciTech News at NTNU

Possible forgiveness comes at a considerable cost. A large part of this cost we bring upon ourselves. (Illustrative photo: Shutterstock / NTB scanpix)

Infidelity can be forgiven – but at a cost

Most people who have been unfaithful do not believe it when their partner says they forgive them. And the fact that men often don’t realize that emotional infidelity is a problem just feeds the conflict.

Gemini, NTNU Trondheim - Norwegian University of Science and Technology

NTNU is the second largest of the eight universities in Norway, and has the main national responsibility for higher education in engineering and technology.

Infidelity is very common. At least 20 per cent of couples – and perhaps many more, depending on where you set the limit – are unfaithful to their spouse.

Being forgiven for infidelity is simply not easy. But many people whose spouse forgives them mistrust the signals and do not really believe that they are forgiven, according to a new study from NTNU.

“We have a strong tendency not to believe our partner when they tell us we are forgiven,” says Mons Bendixen, an associate professor in the Department of Psychology.


Free of charge infidelity is not, because possible forgiveness comes at a considerable cost. A large part of this cost we bring upon ourselves.

Error Management Theory

Making erroneous assumptions on the basis of signals from the physical and social world is the result of natural selection, because the cost of one type of error has been higher than the other throughout evolution.

For example, we may mistakenly believe when we go out walking on a dark autumn night that a long object on the trail is a snake. We may also believe that a smile, laughter or a light touch on the arm from another person means that they have sexual intentions This is what we call overperception or a false-positive error.

The opposite is true with forgiveness. Following a transgression, we get signals from the partner that everything is OK, but we tend to believe that everything is not OK.

These errors lead us to act. We jump away from the object, we respond with a pick-up line and make an advance, or we strive to secure our relationship after the transgression. However, these actions entail relatively low costs.

The alternatives are potentially much more costly. We do not jump away and it’s a poisonous snake, we pass up a sexual opportunity or we continue the relationship as if the transgression has not happened – and suddenly the partner withdraws from the relationship, or break up.

When you do not really believe you are forgiven, even if your partner asserts that you are, you will overcompensate.

You may become more attentive, buy gifts or do other things that you expect your partner will appreciate. Underestimating the degree of forgiveness is probably an evolutionary mechanism, because the relationship may be in danger.

“The cost could be high if you think you are forgiven, but really are not. You might not work hard enough to mend the relationship,” says Bendixen.

Better safe than sorry, it is better to make a little extra effort rather than do too little.

Regardless, the consequences are usually uncomfortable for the unfaithful party. Your partner takes it for granted that you believe what he or she says to be true.

Advantageous to be wrong

In this case, it may be to your advantage to be wrong. The Error Management Theory (EMT), a theory of evolved perceptual errors, can help explain why. (See fact box.)

We can make one of two false assumptions when we interpret signals: we can believe that something exists even if it doesn’t, and we can believe that something doesn’t exist even if it does.

From an evolutionary perspective, it’s a question of which errors are more adaptable.

“An example is men who think women are interested in sex, even though the women’s intention is just to be nice. The most important thing for men in situations like this is not to miss a sexual opportunity,” says Bendixen.

Similarities between the sexes

Most partners aren’t particularly intent on getting revenge or seeing their partner suffer. That doesn’t mean that it never happens, but the probability is the same for both sexes.

They are more likely to pull away and want to keep some distance.

“Partners want infidelity to have a cost, but will rarely respond by being unfaithful themselves,” says evolutionary psychologist Trond Viggo Grøntvedt at NTNU’s Department of Public Health and Nursing.

There is also no difference between the sexes when it comes to whether they would break up with the unfaithful partner or not. This is as likely for women as for men.

The sexes agree on a lot when it comes to infidelity. But one exception exists.

Did I do something wrong?

“Men often do not understand how hard emotional infidelity is on women,” says Professor Leif Edward Ottesen Kennair in the Department of Psychology.

Sexual infidelity strongly affects both men and women. Neither men nor women usually find it acceptable for their partner to have sex outside the marriage.

But say you meet someone at a party and dance and flirt with the person there. Later you meet that person multiple times without telling your partner, but you don’t have sex. A friend of your partner finds out, and even reports that you look like you are in love. Is this wrong?

Women find this scenario much worse than men do.

“Many men do not see this as infidelity at all, since they did not have sex with the other woman,” said Kennair.

Is this a problem? Well, yes, maybe.

Men forgive more often

Men who are confronted with emotional infidelity do not necessarily think that they have done anything wrong. As a result, they do not attempt to make up for anything, at least not as much as if they had been sexually unfaithful. This certainly does not benefit the relationship.

“It can also be a seed for conflict in the relationship,” says Kennair.

At the same time, men are more likely to forgive this form of infidelity in their spouse. Men have less need to distance themselves from their partner than women do, and they look at emotional infidelity as less threatening to the relationship than women do.

The same with jealousy

This matches up with the psychologists’ predictions. Previously, they investigated jealousy reactions in women and men around the suspicion of imminent infidelity. Many of the same patterns were found in that study.

Women become most jealous at the thought of their partner being emotionally unfaithful, whereas men become most jealous in the case of sexual infidelity.

This is again entirely in line with the evolutionary theory of parental investment. For most women, it has been worse for them from both a historical and evolutionary perspective if their partner breaks up with them than it has been for most men.

Becoming emotionally attached to someone other than themselves has therefore been more threatening to women than to men.

Researchers conducted the survey with 92 heterosexual couples. These were young students who answered questions about imagined sexual or emotional infidelity by their partner and themselves. (The questions can be found here.)

Whether these responses would apply to all heterosexual relationships is of course a question. Those asked were young, perhaps inexperienced and idealistic, starting their adult lives, so they could more easily find a new partner than others, and we can assume they knew they would talk to each other about the answers afterwards.

But the conditions were the same for both sexes, and gender differences are nevertheless clear.

Infidelity is named as the most common cause of divorce in Norway, although other reasons often underlie it. Women initiate divorce much more often than men do.

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