Some women spend their whole lives devoid of sex, becoming and dying "old maids" as they used to be called. Some screw one man their whole lives---namely, married women who screw only their husbands. Others have affairs; some become "sex workers," as prostitutes are sometimes called. And women porn stars have their own niches. I'm none of these. I'm not married, nor do I ever intend to be. Yet I have sexual intercourse on...