Infidelity (colloquially known as cheating, adultery, or having an affair) most commonly refers to a breach of an expectation of sexual and or emotional exclusivity expressed or implied in an intimate relationship.
Infidelity can be physical intimacy and/or emotional intimacy. The impact of infidelity is said to relate not only to sex outside a relationship, but also to trust, betrayal, lying and disloyalty. Sexual infidelity by a marriage partner is commonly called philandery, adultery, or an affair.
What constitutes an act of infidelity varies between and within cultures and depends on the type of relationship that exists between people. Even within an open relationship, infidelity may arise if a partner in a relationship acts outside of the understood boundaries of that relationship.
Emotional infidelity is the redirection of emotional resources, such as romantic love, time, and attention, to a person or persons outside a relationship. The level of intimate involvement can extend from in-person involvement to online affairs. Emotional infidelity, as compared to physical infidelity, can inflict as much, if not more, hurt, pain and suffering. Most infidelity involves both physical and emotional unfaithfulness.
Studies suggest around 30–40% of unmarried relationships and 18–20% of marriages are marked by at least one incident of sexual infidelity. Men are more likely than women to have a sexual affair, regardless of whether or not they are in a married or unmarried relationship.
Children can be witnesses to an affair and outcomes of an affair. Between 2–4% of children are conceived as a result of an affair. A 2005 scientific review of international published studies of paternal discrepancy found a range in incidence from 0.8% to 30% (median 3.7%), suggesting that the widely quoted figure of 10% of non-paternal events is an overestimate.
Infidelity which does not involve sex or conception may be referred to as a romantic friendship or an emotional affair. Some people consider virtual sex, which is an on-line relationship, as infidelity.
Each case of infidelity serves a different purpose. Being able to justify the behavior of a spouse and define it will lessen some of the confusion. There are five categories of infidelity:
1. opportunistic infidelity:-example debauchery.
2. obligatory infidelity
3. romantic infidelity
4. conflicted romantic infidelity, and
5. commemorative infidelity
Opportunistic infidelity occurs when a partner is in love and attached to a partner, but surrenders to their sexual desire for someone else. The opportunistic infidelity is driven by irrepressible lust, situational circumstances and/or opportunity, and sometimes, pure risk-taking behavior.
Obligatory infidelity is based on fear that refraining from someone’s sexual advances will result in rejection, and being unwilling to handle such rejection, resulting in surrender to them. Some people end up cheating solely on the need for approval from somebody, even though they still hold a strong attraction to their committed partner.
Romantic infidelity occurs when the cheater is in the process of “falling out of love” with his/her partner. The person’s self-perceived obligatory commitment to the relationship’s tenets and overall life-meaning is likely the only thing still keeping them with their partner in this example.
Conflicted romantic infidelity takes place when a person both falls in love with and has a strong sexual desire for multiple people at one time, even though s/he may already be committed to a partner. In this circumstance the person feels s/he cannot tell his/her committed partner about what has happened, but is in any unable to resist the compulsion; this lack of open discussion is usually what separates conflicted romantic infidelity from things like a well-defined open relationship or polyamory.
Commemorative infidelity occurs when a person has completely fallen out of love with their spouse, but is still in a committed relationship with them.

The transformation of infidelity
Recently, in North America and Europe specifically, there have been drastic changes in the nature and character of relationships. Fewer people are choosing to get married and instead are assuming relationships similar to marriage, without the title. The divorce rates are rising and types of family development are changing. For example, more couples are choosing to remain childless or have children without being married. These transformations may be attributed to the changing labor markets, along with new and different value sets and lifestyles. In societies where marriage is no longer uncritically perceived as a monogamous lifelong relationship, getting married seems a more dubious enterprise.[17] Marriage, sex, and childbearing, which have been a tightly bound package for much of the 20th century, are no longer so inextricably linked.
Defense mechanisms to prevent infidelity
Game theory, suggests that cheating is actually the Evolutionary Stable Strategy for an individual to improve his or her own fitness (Roughgarden and Akcay, 2010). This holds true in most mating systems and shows that infidelity is actually advantageous to a cheating male’s fitness. It allows men to copulate with multiple women, maximizing the number of offspring in the next generation (Roughgarden and Akcay, 2010). So why don’t more humans cheat? What defense mechanisms do mates have that prevent infidelity in their partners? Current research in the field provides three suggestions to explain this phenomenon. The original theory proposes that jealousy acts as an innate and adaptive response to prevent infidelity (Buss et al., 1992). Critics of this theory propose an idea that infidelity is prevented through social monitoring of one’s mate and action once there is a violation of expectation (Harris, 2004). The most recent theory suggests that punishing cheaters and damaging their individual reputations are what police infidelity (Hirsch et al., 2007).
The more traditional Evolutionary Psychological viewpoint on how infidelity is prevented is through the adaptively developed emotional response of jealousy. Jealousy is an emotion that can elicit strong responses. Cases have been commonly documented where sexual jealousy was a direct cause of murders and morbid jealousy (Harris, 2003). Buss (2005) states that jealousy has three main functions that can help prevent infidelity.
It can (i) alert an individual to threats with a valued relationship,
(ii) be activated by the presence of interested and more desirable intrasexual rivals,
(iii) function as a motivational mechanism that creates behavioral outputs to deter infidelity and abandonment.
Looking at its physiological mechanism helps support this idea. Jealousy is a form of stress response which has been shown to activate the Sympathetic nervous system by increasing heart rate, blood pressure, and respiration (Harris, 2000). This will activate the “fight or flight” response to ensure action against the attempt at sexual infidelity in their partner (Buss, 1992). Buss and his colleagues (1992) were the first to pioneer a theory that jealousy is an evolved human emotion that has become an innate module, hard-wired to prevent infidelity from occurring. This idea is commonly referred to as Jealousy as a Specific Innate Module (JSIM) and has become widely debated (Harris, 2003). The basis behind this argument is that jealousy was beneficial in our ancestor’s time when cuckoldry was more common (Buss et al., 1992). They suggested that those who were equipped with this emotional response could more effectively stop infidelity and those without the emotional response had a harder time doing so. Because infidelity imposed such a fitness cost, those who had the jealous emotional response, improved their fitness, and could pass down the jealousy module to the next generation (Buss 1996). This provided an ultimate selection mechanism to make this module adaptive and still persist in today’s human population.
David Buss and his colleagues (1992) tested this pioneering hypothesis through self-report, forced-choice studies in college students which was explained in a previous section on the Gender differences in infidelity. Their findings support the JSIM theory since our ancestor’s concerns of paternal uncertainty and parental investment are reflected in modern humans through the subjects’ sex-related responses and anxieties. It suggests that jealousy is adapted to prevent these respective fitness reductions from infidelity in males and females (Buss et al., 1992).
The hypothesis that jealousy evolved into an innate module that is hard wired into human brains is widely accepted but is also met with a lot of controversy. Aside from the experimental flaws and possibility of unreliable data, social-cognitive researchers argue that jealousy can’t be an adaptation to prevent infidelity (Harris, 2004). Christine Harris (2005) states that the fitness advantage of jealousy is not as clear as Buss reports. She speculates that in our ancestor’s times, the act of sex or emotional infidelity is what triggered jealousy. Therefore the signal detection would have happened only after infidelity had occurred, making jealousy an emotional by-product with no selective function. These Social-cognitive researchers believe that a more accurate way to prevent infidelity is by social monitoring and acting upon any violation of expectations. They hypothesize that a person monitors their partner’s actions with a potential rival through primary and secondary appraisals (Harris, 2004). If their expectations are violated at either level of observation they will become distressed and enact an appropriate action to stop the chance of infidelity (Cramer et al., 2008). It allows them to act accordingly before infidelity occurs, thereby having the capability to raise their fitness (Harris, 2004). This can be likened to mate guarding in primates but to a much lesser degree. Harris’ hypothesis was tested by Cramer and his colleagues (2008) using the same survey technique that Buss used, only with both forced-choice and mutually-exclusive surveys. They added an Infidelity Expectations Questionnaire (IEQ) to determine the subject’s current expectations of their relationship prior to the violation of expectations from the Buss survey. After adding this factor and adjusting the original results with the new survey results, social-cognitive researchers would expect no sex differences in responses. However, the results showed a clear sex difference, thereby supporting Buss’ original research results and idea of an innate sex-difference in jealousy and infidelity. More research and evidence need to be provided for the social monitoring theory to be considered in the field.
A recently suggested defense mechanisms of infidelity that is attracting more attention and research is the idea that a particular social group will punish cheaters by damaging their individual reputation (Fisher et al., 2009). The basis for this suggestion stems from the fact that humans have an unmatched ability to monitor social relationships and inflict punishment on cheaters, regardless of the context (Scheuring, 2010). This punishment comes in many forms, one being social gossip of the action. Social Gossip will ostracize that individual from the group by damaging his or her reputation. This damage will impair the future benefits that individual can confer from the group and its individuals (Scheuring, 2010). Punishment actually encourages group cohesion and cooperation. A damaged reputation is especially debilitating when related to sexual and emotional infidelity because it can limit future reproductive mate choices within the group and will cause a net fitness cost that outweighs the fitness benefit gained from the infidelity (Fisher et al., 2010). This will deter an individual from cheating in the first place. A good example of this is given in fieldwork done by Hirsch and his colleagues (2007). They did observational research on the influence of reputation and sexually transmitted disease (STD) risk on sexual practices of the villagers in Degollado, Mexico. What they found was that gossip about extramarital affairs was particularly prevalent and devastating for reputation in this region because of the small community. Adultery can cause an individual to be disowned by the family, hurt the marriage value of his/her family, lose money or a job, and diminish future reproductive potential. Men having extramarital affairs had to be extremely tactful by having these sexual relations in private areas where women don’t go (like bars or brothels) and with women not connected to the community (wandering prostitutes). These are the riskiest areas and the riskiest people to have sexual relations with, making it highly likely to contract and spread HIV/AIDS through these practices. This study shows the power of reputation on an individual because the men of the village value socially safe sex over physically safe sex. In other words, they value their personal reputation over their own well-being since it may confer an increased fitness benefit.
Arguments over these different hypotheses seem to lack progress due to a need for well designed experiments that provide more reliable and conclusive results. Further attention and innovative research towards these major arguments can help elucidate the role of infidelity defense mechanisms in modern human societies.
Responses to Infidelity
Divorce is one response to marital infidelity. Another would be to seek couple’s therapy or counseling. With time to heal and the mutual goal of rebuilding the relationship, some couples emerge from infidelity with a stronger and more honest relationship than before. Relationship counseling can help put an affair into perspective, explore underlying relationship problems, learn how to rebuild and strengthen a relationship, and avoid divorce – if that is the mutual goal.
Marriage counseling is generally provided by licensed therapists or clinical psychologists known as couple, marriage or family therapists (see family therapy and emotionally focused therapy). These therapists provide the same mental health services as other therapists, but with a specific focus – a couple’s relationship.[40]
Relationship counseling typically brings partners together for joint sessions. The counselor or therapist helps couples pinpoint and understand the sources of their conflicts and try to resolve them. Partners evaluate both the good and bad parts of their relationship. Integrative behavioral couples therapy has shown success in increasing intimacy after an affair.
Intimate betrayal inflicts an attachment wound and this is sometimes irreparable, particularly when both partners are not committed to repair.
In her research, Candyce Russell, a licensed family therapist developed three Emotional Stages that typically follow an incident of infidelity:
Stage one: roller-coaster a time filled with strong emotions, ranging from anger and self-blame to periods of introspection and appreciation for the relationship.
Stage two: moratorium a less emotional period in which the cheated-on spouse tries to make sense of the infidelity, obsesses about details of the affair, retreats physically and emotionally from the relationship, and reaches out to others for help.
Stage three: trust-building for couples who decided they wanted to stay together and make their marriage work. In this stage, “showing commitment to the relationship was most important for injured parties to begin forgiving and building trust,” Russell said.[41]