The first one gives us a good overview.
Sex Differences in Self-reported Infidelity and its Correlates - Rebecca J. Brand & Charlotte M. Markey & Ana Mills & Sara D. Hodges - 2007
One of the most common findings in infidelity research is that males commit more acts of infidelity. These sex differences apply to the prevalence of infidelity (the number of individuals who report having cheated), and although studied less exhaustively, the incidence of infidelity (the number of cheating liaisons in which an individual engages). [...]
When definitions of cheating include non-intercourse behaviors such as kissing or dating, sex differences appear to be attenuated or disappear (Drigotas et al. 1999; Glass and Wright 1985; Wiederman and Hurd 1999). These behaviors, which are sexual or romantic in nature but fall short of intercourse, are still likely damaging to the relationship and certainly violate many people’s
expectations for their relationships. As evidence for this, Drigotas et al. (1999) asked college students if emotional and physical intimacy behaviors, including flirting, sharing feelings, and kissing, constituted infidelity. Most (76%) reported that they did. [...]
In addition, sex differences in infidelity may be changing in recent years. Wiederman (1997) for instance, found that 23% of men and 12% of women had had an extramarital sexual affair. However, when they examined their data separately for participants under the age of 40, the sex differences in infidelity disappear. Allen et al. (2005; see also Oliver and Hyde 1993) reviewed several studies
showing a shrinking sex difference in successively younger cohorts. Therefore, any attempt to understand sex differences in the predictors and consequences of infidelity requires an up-to-date assessment of incidence and prevalence.
In short, cheating has been a different beast in the past and is now getting (more) equal. There is however difference in the perception of emotional and physical cheating which we will analyze in different surveys soon. To continue with the above study.
In fact, in both Study 1 and 2, women appeared to be the more likely sex to report a higher prevalence of infidelity. Our findings seem to indicate that past sex differences reported in this literature may be misleading or outdated. The specific definitions of cheating used in this research and the inclusion of non-intercourse behaviors as cheating behaviors may at least partially account for the finding that women were likely to report infidelity. It is also possible that we are picking up on a cohort effect. The expression of female sexuality is increasingly depicted in popular culture (e.g., television) as appropriate; virginity is not prized as it once was (Buss et al. 2001; Hoyt and Hudson 1981). Thus, women may find themselves feeling free to partake in not
only multiple sexual relationships throughout their lifetime, but perhaps multiple romantic and sexual relationships at the same time, regardless of their current relationship status. [...]
While approximately equal numbers of men and women in our study appear to be cheating, typically, men who were unfaithful cheated many times [...] Women seem more likely to engage in long-term (although adulterous) relationships while men are more likely to engage in one-night stands (Schmitt 2003). Despite this change in measurement tactic, we found that men reported more episodes on average, even though they did not have higher prevalence overall. [...]
Consistent with our hypothesis, women’s relationships were more likely than men’s to break up after their own infidelity. Further [...] we have some evidence [...] that women may be more likely to begin a new relationship with their extra-pair partner than are men. Both of these findings support the idea that women are cheating to mate-switch. [...] Although men and women reported many of the same reasons for cheating (that they were attracted to the extra-pair partner, that they were bored or unhappy in the current relationship), there were also some telling differences. One of men’s top-five responses that did not appear in women’s top-five was that they cheated out of opportunity. This is consistent with the possibility that at least some men are pursuing a strategy of quantity, mating with multiple partners without a lot of regard for quality. On the other hand, women were significantly more likely than men to report cheating because they were unhappy in the current relationship and because they were made to feel attractive by the extra-pair partner. Both of these reasons are consistent with women cheating as a way to find a better, more attentive partner than their current mate.
Popular culture conceptualizes women as loyal, faithful caretakers of the men in their lives, while men are conceptualized as creatures with uncontrollable urges that force them to “sow their seed.” Past research has also suggested that men are more likely to be unfaithful than women. However, the present findings suggest that this notion may be old-fashioned and outdated. Our findings
suggest that women do not appear to be altogether less likely to be unfaithful than men. [...] Despite equal prevalence of cheating, our findings support the idea that men and women may cheat for different reasons. Men who cheat seem likely to be pursuing a quantity-over-quality strategy; if they select cheating as a strategy, they may do so merely out of opportunity, with many different women.
Women, on the other hand, may be using infidelity to mateswitch; rather than cheating indiscriminately with a large number of men, they may be selective in choosing a better potential long-term mate, specifically one who will make them happier than their current partner and will validate their attractiveness. Thus, while infidelity may have devastating consequences for both men and women in relationships, different measures may be effective in preventing men’s and women’s cheating behaviors and different ramifications may follow men’s versus women’s acts of infidelity
Before we start with the other studies, in retrospect it is interesting to me to see how these all fit together. I will spoil it, to women it seems the emotional connection is more important than the sexual one. So what does the next study tell us:
Sex differences (and similarities) in jealousy The moderating influence of infidelity experience and sexual orientation of the infidelity - Brad J. Sagarina, D. Vaughn Beckerb, Rosanna E. Guadagnob,
Lionel D. Nicastleb, Allison Millevoib - 2003
Thus, ensuring that putative offspring are indeed one’s own is an adaptive challenge for males, whereas a female faces the different challenge of ensuring that the father invests resources into her children rather than those of rivals. These considerations suggest that male and female sexual jealousy will be qualitatively different (Daly, Wilson, & Weghorst, 1982; Symons, 1979).
Accordingly, Buss, Larsen, Westen, and Semmelroth (1992) predicted that men and women would differ in their responses to emotional and sexual infidelity, with women being relatively responsive to the former and men to the latter. Both survey and physiological evidence supported this hypothesis: when asked which type of infidelity would distress them more, men were much more likely than women to select the sexual infidelity, and when subjects were instructed to fantasize about one type of infidelity or the other, measures of electrodermal activity and heart rate supported the conclusion that the sexes differed in the two types of infidelity’s relative emotional impacts.[...]
Male victims of infidelity were significantly more likely than male non-victims to report greater distress in response to a sexual infidelity. Furthermore, in contrast to the typical 40–50% ratio
for men on the forced-choice question, nearly two-thirds of male victims of infidelity indicated that a sexual infidelity would cause greater distress. For women, experience as a victim of infidelity did not serve as a moderator, but experience as a perpetrator did. Women who reported cheating on a past romantic partner were significantly more likely to indicate that a sexual infidelity would cause greater distress compared to women who had not cheated. [...] From this evidence, we suggest that it is inaccurate to view men and women as manifesting a gross, context-free sex difference in jealousy. Our results suggest that when men and women face differential adaptive challenges—when their partners become involved with members of the opposite sex—they display a large, reliable sex difference, but when conception is not a possibility—when their partners become involved with members of the same sex—the differential adaptive challenges disappear, and so do the sex differences.
Forgiveness or breakup: Sex differences in responses to a partner’s infidelity - Todd K. Shackelford, David M. Buss, Kevin Bennett - 2002
Although many factors contribute to the complex decision to forgive or break up following a partner’s infidelity, work guided by an evolutionary perspective suggests that the decision may hinge on the nature of the infidelity (e.g., Buss et al., 1992; Daly, Wilson, & Weghorst, 1982; Symons, 1979). Among human ancestors, a single instance of sexual infidelity could jeopardise a man’s certainty in paternity, with the attendant reproductive risk of investing a couple of decades of effort in a rival man’s child rather than his own (see Geary, 2000, for a recent discussion of paternal investment). From an ancestral woman’s perspective, a single sexual infidelity committed by her husband would not have carried this magnitude of risk, since her genetic maternity is not thereby compromised and hence her investments would still have been channelled toward her own genetic children. If her husband became emotionally involved with another woman, on the other hand, such affective infidelity would signal the long-term diversion to that other woman of her husband’s energy, commitments, and investments, and hence would be more reproductively costly.
If these selection pressures recurred over human evolutionary history, selection could have created decision-rules to forgive or break up depending on specific features of context such as the nature of the infidelity and the sex of the person committing the infidelity. [...]
The results of this research support the hypothesis that forgiveness or breakup depends on the sex of the respondent and the nature of the infidelity. Men, relative to women: (a) find it more difficult to forgive a partner’s sexual infidelity than a partner’s emotional infidelity; and (b) are more likely to break up in response to a partner’s sexual infidelity than in response to a partner’s emotional infidelity. Conversely, women, relative to men, find it more difficult to forgive and are more likely to break up with a partner who is emotionally unfaithful. These sex differences remain even after controlling for effects attributable to ethnicity and to age. Over human evolutionary history, both sexes incurred reproductive costs as a result of
a partner’s sexual infidelity and emotional infidelity. These costs are sex-differentiated, however. A partner’s sexual infidelity placed men, but not women, at risk of investing resources in a rival’s offspring. A partner’s sexual infidelity therefore represents a potentially more costly adaptive problem for men than for women. Modern men have psychological mechanisms that are exquisitely sensitive to a partner’s sexual infidelity (Buss et al., 1992; Daly & Wilson, 1988).
Women also are sensitive to a partner’s sexual infidelity, but accumulating evidence suggests that women become more upset in response to a partner’s emotional infidelity, which signals the long-term diversion of a partner’s commitment and investment (Buss et al., 1992; Buunk et al., 1996; DeSteno & Salovey, 1996; Geary et al., 1995; Wiederman & Allgeier, 1993; Wiederman & Kendall,
Not that is a much better post on cheating.