In that study which involved 19,065 people during a 15-year period, rates of infidelity among men were found to have risen from 20 to 28%, and rates for women, 5% to 15%.A survey conducted in 1990 found 2.2% of married participants reported having more than one partner during the past year.In marital relationships, exclusivity expectations are commonly assumed although they are not always met.When they are not met, research has found that psychological damage can occur, including feelings of rage and betrayal, lowering of sexual and personal confidence, and damage to self-image.In general, national surveys conducted in the early 1990s reported that between 15-25% of married Americans reported having extramarital affairs.Treas and Giesen found that people who had stronger sexual interests, more permissive sexual values, lower subjective satisfaction with their partner, weaker network ties to their partner, and greater sexual opportunities were more likely to be unfaithful.One measure of infidelity among couples is the frequency of children secretly conceived with a different partner, leading to "non-paternities".Such covertly illegitimate children amount to about 1–2% of newborns in studied populations.
Those that posit a sex difference exists state that men are 60% more likely to be disturbed by an act of sexual infidelity (having one's partner engage in sexual relations with another), whereas women are 83% more likely to be disturbed by an act of emotional infidelity (having one's partner fall in love with another).
Support for this theory comes from evidence showing higher divorce rates in countries with lower sex ratios and higher monogamy rates in countries with higher sex ratios.
Differences in sexual infidelity as a function of gender have been commonly reported.
Depending on the context, men and women can experience social consequences if their act of infidelity becomes public.
The form and extent of these consequences are often dependent on the gender of the unfaithful person.