Our friend is taking a new course in life. She is learning to Live Alone.

She has, we tell each other, all the prerequisites for enrollment -- the right background, the right training:

As a young woman she had graduated from parents to husband without a day of private schooling.

For 19 years she had majored in togetherness.

When her marriage ended six months ago, it was only natural that she would embark on a crash course in independent studies.

Because our friend is a tough grader, she has told us: "I flunked marriage." The truth is that she dropped out, that they both dropped out. But the sense of failure is an honest one.

There was something else. In those last months of marriage she was haunted by the idea that sooner or later she would have to be alone and that she was unprepared. She had missed some sort of survival training that should have been a required course when she was younger. She expressed a sense of growing urgency. She had to learn to about it now . . . while she still could.

So, today, our friend is a determined student, even a grind at times, compelled by the need to pass this course in adult education.

Well, we are both graduates and post-graduates, and we understand as we watch. She has done her homework, passed the quizzes, crammed for midterms. Cooked and eaten three-course meals by herself. Spent an entire week-end alone. Dealt with household emergencies, and checking accounts. Faced down half a dozen panicky moments of loneliness and self-centeredness.

We go down the checklist, nodding with approval at our friend's studies. She has gone back to basics. Even the new man who had met her and cared for her understood that she was not ready for doubles. She was still learning, slowly, about number one.

The two of us, her friends, quote statistics at each other and at her. Twelve percent of the population lives alone at one time or another. More than 20 percent of the households in America consist of one person. One out of three marriages ends in divorce. The average wife outlives her husband by a decade.

We are realists, pride ourselves on it, and the figures tell us that sooner or later the odds are on aloneness. We have encouraged her to accept it. We have offered her a bumper-sticker truth: you have to be able to live with yourself to live with anyone else.

It occurs to me that this is our security. If one generation wanted to learn typing or teaching as "something to fall back on," now we regard Learning to Live Alone as some sort of strange security.

We take it for granted. We encourage each other and our children to learn it when they are younger. We understand when our friends enroll for refresher courses.

But I wonder about it all. Not so long ago, aloneness was regarded as a temporary condition. It was suspect. At the time of the American Revolution, less than 4 percent of the households contained only one person.

Even now in other places and other cultures aloneness is an oddity, an accident, an illness more than a luxury. Through human history, people have lived in clusters where their only privacy was in their thoughts. The Samoans did not set up single shelters. The Chinese do not learn to live alone. Hardly.

It's possible that aloneness is, in part, a modern American elective. We fall into it and, yes, we sign up for it in droves: the working young, the divorced, the widowed. Those who can afford to live by themselves choose to.

The reality resounds through the course-of-life catalog. In fact, like our friend, we are driven now by an uneasy feeling that togetherness may be only a pause between single states. That anxious sense of what is basic has shifted. pThe bottom line seems to have moved.

Yet I wonder sometimes whether we struggle to protect ourselves from loneliness by liking it. Whether this independent study is an advance or a retreat. I wonder whether it is some American madness or self-improvement bravado.

Yes, I guess it is necessary for our friend to learn to live alone now. But if it felt good, would she have to study so hard?