I talked to my mother-friend the other day--pretty much the only one I know--and she was asking if she could use me as a reference. "Of course," I said, and then I asked her how her week had been. "I went to a Mommy-and-Me today. It was pretty funny."

I was completely impressed. "You're always going to these Mom things. You're much more disciplined about that crap than me."

"I have to," she said, with a hint of desperation. "I'm so lonely!"

Her confusion was palpable over the phone. She was once, not so long ago, a hip young bartender, newly married to a popular musician. Now she was a hip new mom, but all her cronies were still in the bars or the clubs.

Her frustration rose. "I make plans with my old friends, but they don't understand. I can't be spontaneous like I used to, and when we make a date to go somewhere, they just hop in the car and go. For me, I have to find a sitter or make sure my husband's around to watch the kid, and then pump enough milk so that I can have a couple of drinks without worry. So I do all that, I'm ready to go, and they cancel on me. They can just go out again the next night. I have one window of opportunity, but then I have to start planning all over again."

These are not earth-shattering problems. But I understood her sense of abandonment, her feeling of isolation. Our names are now uttered fondly on the lips of our friends, but it's been so long since we've been able to go out past 8:00 pm that we're in the "Where are they now?" file, dropped out of the society of the sociable and into the society of the has-been.

When we came home from the hospital, my husband and I went into a period of deep hibernation. The light refracted differently; parents who days earlier didn't exist now were walking to and fro in our neighborhood, the invisibility cloak lifted from them like magic. I saw strollers and car seats and snugglis. Toddlers squealed in yards which, I could swear, were empty of tiny voices the week before. The world was populated with babies, and I hadn't seen a single one before my own made an appearance.

But when the children were magically revealed, I sensed, even then, that a chapter closed. I didn't know which one, but I was pretty sure that an era was winding up with my friends. It was always going to be more complicated socially. It is hard to not be nostalgic about that, though I have no regrets about parenthood.

The other day my pipes rusted through, and a friend was planning on coming over to check it out for me. He said, "We threw a bunch of steaks on the barbecue--you should come over and hang out." I looked at the clock. It was just nearing 8:00 pm. The bun was asleep. I had already eaten dinner and was planning on going to bed in three hours. "I'm sorry, I'd loved to. But the bun's already in bed," I explained. "Oh, of course," he said.

But I knew he had forgotten.

For one brief minute I flirted with spontaneity. I could have hopped in my car and hung out to the wee hours of the morn. I could have had numerous cocktails, gotten lit, acted like a buffoon and stumbled back home, no repercussions.

I missed it, but then I went and put a blanket on the bun. It is a difficult social adjustment. But it's worth it.