My sister, who lives in the UK, has recently moved into in a charming, if slightly ramshackle apartment with her fiancé. The charm comes from the sunlight streaming through stained glass windows, the ramshackle aspect from the bath, which emits a paltry drizzle of water that alternates from scalding hot to glacially cold. But that’s England for you.

Out to lunch with Anna, a new friend, my sister heard about how Anna and her boyfriend of six years were going to try and have a baby in the spring. “That’s great!” my sister exclaimed, but then thought to ask, “So are you two going to finally move in together?” Anna baulked. “Not if I can bloody help it!” For Anna, things are perfect as they are. She loves her boyfriend, yes, but she doesn’t need him around all the time. In fact, she likes that he has ...