So, why does good sex so often fade, even for couples who continue to love each other as much as ever? And why does good intimacy not guarantee good sex, contrary to popular belief? Or, the next question would be, can we want what we already have?That's the million-dollar question, right? And why is the forbidden so erotic? What is it about transgression that makes desire so potent? And why does sex make babies, and babies spell erotic disaster in couples?