You have to love the caution with which academics, forced by data, endorse stereotypes:
It is believed that men, in contrast to women, are more likely to cognitively separate sex from love (Banfield & McCabe, 2001; Duncombe & Marsden, 1999), and though investigators disagree as to the causes (biology, social conditioning, or a combination of both), available findings seem to reflect this tendency. In a sample of 253 heterosexual men and women, men were significantly more likely than women to report engaging in ongoing sexual relationships without wanting emotional involvement (Townsend, 1995). Compared with women, men have been found to be significantly more likely to approve of sex in a casual relationship (Hyde & Oliver, 2000) and to consider having sexual intercourse with a stranger (Buss & Schmitt, 1993). Glass and Wright (1985, 1992) found that over half of the men in their sample who had extramarital sex stated that their marriages were actually happy or very happy and that they pursued extramarital relationships for sexual excitement rather than emotional fulfillment. When 844 gay, lesbian, and hetero-sexual respondents were asked their reasons for engaging in sexual behavior, men (both gay and heterosexual) were more likely than women (both lesbian and heterosexual) to give reasons that emphasized sexual pleasure and recreation rather than intimacy (Leigh, 1989).
The passage, sent along by a friend, is from the article “Extradyadic Sex and Gay Male Couples: Comparing Monogamous and Nonmonogamous Relationships.”