Are friendships with opposite sex friends within couple friendships possible? Our research in Two Plus Two: Couples and their couple friendships shows that it is but with some caveats. We asked men who were partnered or married how many men friends they have and how many women friends they have. Men reported an average of five men and two women friends. Women, when asked how many friends they have reported the reverse: an average of five women friends and two men friends. While it is often stated in the research that women have more friends than men, this was not born out here. But when looked at more closely we did learn that men and women, in the context of couple friendships, did report they have friendships with both members of the couple (we only interviewed heterosexual couples and two-thirds of our couples were married, one-third partnered and in a live-in relationship of at least one year's duration). Some of these couple friendships were characterized as equal balanced, meaning that they considered themselves close friends with both members of the couple. This is in contrast to couples who felt that one spouse in each other couples was driving the friendship and that the other spouse was more an appendage. These particular equally balanced couples also often felt that such relationships could be characterized as emotionally-sharing, that is, both partners felt they could talk openly about feelings with both members of the couple.
More typical were couple friendships that were fun-sharing. In these relationships couples "just wanted to have fun" (apologies to Madonna) with another couple and not get into emotionally-laden material when they were socializing. These fun-sharing couples may have very close relationships with each other or with individual friends with whom they were sharing their emotions.
Further, individual friendships between women and men are more likely early on in a marriage/partnership than later on. We believe this is because just before people get into long-term relationships, they are maintaining a number of opposite sex friendships. These often continue into the early years of the partnership/marriage and then tend to fade out as people have been married 10, 20, and 30 years.
So, one way to make opposite sex friends is to do it in the context of a couple friendship with another couple. This seems to be a safe way to have access to such relationships that can give you insight into the opposite sex (while also socializing with your own partner).