A few months ago, one of my best friends told me that she and her boyfriend had gotten engaged. Engaged? I thought. What for? She has two young kids and has never been married; he’s older; they each have their own apartment; she seemed happy with the way things were. “Congratulations!” I said, because he’s a good person, and I love my friend. Then I asked where they were going to live, and she laughed in my face. “Oh, we’re not moving in together,” she said. She’d assumed I would have known