Dear Liza, 
 I’m a 32-year-old woman who would like to have kids and a life partner in the not-so-distant future. And lucky me! I’ve recently started dating an excellent candidate. But I can’t even pretend to think it’s possible (or desirable) to have sex with just one person for the rest of my life or even, frankly, for a few years. 
 Monogamy feels antithetical to the type of feminism and anticapitalism I subscribe to. I am repulsed by the idea of being a man’s property. Also, monogamy—like capitalism—requires us to believe in a false scarcity: that we have...