Men and women who have a "friendship" that revolves around sex, or at least the pursuit of sex, don't have a real friendship. That said, leaving sex out of the equation, men and women can indeed genuinely be friends. But one must understand that the more a man and a woman establish a genuine friendship with each other, the more at least one of them might believe they found their soulmate and as a result will want to upgrade the relationship more than what it is. Every single woman who I was close friends with over the years has eventually proposed the idea of us being in a relationship, to which I rejected and still maintain a very close friendship with them today.