Friendships between genders often lead to marriage, but once it does, outside friendships between men and women can complicate people's lives. And the complication is often sexual attraction. For about 25 percent of middle-aged men and 45 percent of middle-aged women, an opposite-sex friendship is not OK with the spouse. The spouse may be onto something. There are, indeed, people who may profess friendship but intend to steal another's mate. About half of 236 college-age men and women surveyed in a June 2001 study in the Journal of Personality and Social Psychology said they had tried to attract another's partner at least once. And 85 percent of them said someone had tried to attract them away from a mate at least once. The gossipy mess that results has a term, coined in the book "The Evolution of Desire: Strategies of Human Mating," by David Buss, psychology professor at the University of Texas at Austin. The term is "mate poaching."
Los Angeles Times
Married, With 'Just Friends'