I regularly get all giddy and Tiggerish about how far lesbians and gay man have come from the bad old days of, say, the late 1970s when I came out. Back then, most of the mainstream didn’t quite notice we were human. I do remember the moment I first realized that I wanted to kiss a girl, and my stomach fell out of me with fear: I didn’t want to be one of them. It’s hard to convey to you all how different things are and how far we’ve come. I’ve been thinking about this because, on her Bloggingheads show last week, Sarah Posner asked me whether, ten years ago, I would have imagined we’d be as far along as we are on marriage. Ten years ago, yes. In 2002, it was pretty clear what path we were on. But in the 1970s, marriage was simply beyond conceivable. If you want some evidence, you can find it in an old All in the Family episode in which Edith loses her beloved cousin Liz —and learns that the cousin’s “roommate” was in fact her partner. I looked back at it recently when Dan Savage...