The question that arises on my husband’s birthday is always the same: “What do you get for the man who has everything?” He isn’t a shopper. He once declared he has enough trousers to last the rest of his life. So for his 40th, I decide to buy him a vintage watch. It would declare to the world that — despite his tattered sweaters — he’s an employed adult. But when I mention the watch, he says that what he really wants isn’t a good but a service: a threesome with me and another woman. I’m not exactly shocked. He’d...