It has been argued that limiting sex to socially sanctioned partnerships like marriage contributes to the stability of the relationship, because it makes the union the unique focus of self-disclosure and sexual pleasure. The emphasis on sexual fidelity, however, varies from culture to culture. Around the globe, about half of societies have strong prohibitions against extramarital sex for women, and about a quarter object strongly to extramarital sex for men (Frayzer 1985). Extramarital sex is permissible for men in half of societies, but it is permissible for women in only one quarter. This double standard—controlling female sexuality more than male sexuality—has been traced to the desire to insure the paternity of heirs. It has also been attributed to the unequal power between the genders— inequality that supports a man's sense of ownership over a woman. Masculine roles, by contrast, often encourage sexual adventuring. For example, brothel visits are a common ritual of male camaraderie in Thailand and elsewhere.
Monogamy, the institutional form of marriage permitting only one spouse at a time, still confronts extramarital relationships, particularly for husbands. La casa chica, or little house, is an established Latin American custom whereby married men maintain a second partner and family. Although polygamy, the custom of taking multiple wives and concubines, is illegal in China, the tradition has made a comeback among businessmen, who can afford to maintain a young mistress in her own apartment. These institutions, of course, still serve to protect the family and the marital relationship by minimizing the intrusion of secondary partnerships. Even in societies where extramarital relationships are casual and fleeting, a degree of secrecy and discretion usually surrounds the activities to minimize marital disruptions.
In honor-based Arab societies, which place a high value on female chastity, relatives may feel obliged to put an unfaithful wife to death. In other societies, casual sexual liaisons outside marriage are widely accepted both for men and for women. This is the case in parts of Africa. Where children are regarded as belonging to broad kinship groups, there may be less concern with paternity and with controlling female sexuality. Where financial responsibility for offspring falls to women, they often rely on supportive sex partners in order to provide for themselves and their children. In urban Nigeria, for example, two-thirds of men and one-third of women in monogamous marriages reported that their most recent sexual encounter was with someone besides their legal spouse.
The less tolerant attitudes in Western nations may be traced to Christian teachings on marriage and sexuality. In the twenty-four largely Western and industrial countries in the 1994 International Social Survey Program, most people stated that extramarital sex was "always wrong" (Widmer et al. 1998). Fully 80 percent of U.S. respondents condemned extramarital relations as being always wrong, a figure comparable to conservative Catholic populations like Ireland (80%), Northern Ireland (81%), and the Philippines (88%). The "always wrong" response found less favor in other countries: Australia (59%), Austria (67%), Bulgaria (51%), Canada (68%), Czech Republic (43%), Germany (data reported separately: East Germany, 60%, and West Germany, 55%), Great Britain (67%), Hungary (62%), Israel (73%), Italy (67%), Japan (58%), Netherlands (63%), New Zealand (75%), Norway (70%), Poland (74%), Russia (36%), Slovenia (57%), Spain (76%), and Sweden (68%). On average, however, only 4 percent of survey respondents believed that extramarital sex was "not at all wrong." Thus, moral judgments in Western countries continue to support sexual exclusivity between husbands and wives.
Although people in the United States have become increasingly tolerant of premarital sex and homosexual sex, they voice stronger disapproval of extramarital sex. Disapproval has actually increased in recent decades. According to data from the General Social Surveys, extramarital sex was condemned as "always wrong" by 70 percent of U.S. respondents in 1973. Following a sharp increase in disapproval at the end of the 1980s, perhaps in response to the AIDS crisis, views on extramarital sex largely stabilized and stood at 81 percent strongly disapproving in 1998.
Permissive sexual values reflect liberal religious and political ideologies. Men are more permissive than women. People with more schooling are more tolerant than people with less education. African Americans and people who live in big cities are also more tolerant of extramarital sex. Not surprisingly, people with permissive sexual values are more likely to have adulterous relationships. Only 10 percent of U.S. respondents who say extramarital sex is "always wrong" report having extramarital sex, as compare to 76 percent of respondents who say extramarital sex is "not at all wrong" (Smith 1994).