“One loves not just the happy memories. At a certain point in life, one is aware that one simply loves one’s memories,” wrote the novelist Natalia Ginzburg.

And that was the thing about my sister. She had been there for all of them. After she died, just over a year ago, my memories were all sad ones. The last hard days, the letting go.

Then, so slowly I didn’t notice them returning, other images began to reappear.

Long summer afternoons, birthday dinners, and singing the Miss America theme song in the bathroom. Shorthand jokes. The rainy night we looked for my lost tooth under a pile of wet leaves.

Then, too, were our fights in the car, parents’ lives and parents’ deaths. A shared moral compass, a sense of humor. Landscapes and decades. Wrong turns. Failures. Diminishments. The interesting thing was, the older we got, the less any of that mattered.

As time went on, the sting had gone out of all of them. Whatever selves we had tried on in our life had been folded in, like egg whites into the batter.

What bound us together was not that we always liked each other. Because we didn’t. It was the certainty of each other, knowing that no matter what, she’d be there. Whether harm was coming from the outside world or inside our selves.

“I’ll miss you,” she said the day before she died, and that’s when I knew. This was going to be far worse than I thought. Not only was I going to lose her, I was going to lose all the reflections of me that came from her eyes.

As the weeks went by, my sorrow took the form of a solitary retreat with no idea where to go or why. A year passed and early one winter morning, I was in bed staring at the white walls of the sky. We had been a family of two, so the answer to letting go of my sister was still no.

When my father died 45 years ago, my mother sat at his bedside crying that she couldn’t imagine life without him. “I know you’ll always love me, ” he told her, “but I can’t bear to think of you wasting your life in misery.” He said that when his father died, his young mother turned bitter and unhappy. “Promise me, that won’t be you.”

The opposite of love, I think, is loneliness. One ties you to the center of the universe, the other cuts you off. Good friends came to get me. Slowly, I tried. Dinner, emails, joining them on short holidays, taking a friend’s son to college. Raking leaves.

Still, there was a reticence on my part, a hidden awkwardness. Not to overstay my welcome or use up my invitations. Scanning their faces for signs of weariness. I said thank you and would you mind, and kept on my best behavior, which can be exhausting.

I didn’t dare wear my torn leggings and black socks to breakfast, wipe my runny nose with my sleeve or throw a hissy fit. I didn’t keep anyone up late going over something I was writing or have a family joke told about me. The truth with a side of tenderness.

What is it really that makes us feel secure with our families, or with those who are like family?

To feel that we are valued, that we are not cast adrift. To trust we can be ourselves, and that all our many selves will be part of an ongoing story. To share the solace of being human. And know there is a place we will hear, as we slide into home, the umpire call, “Safe.”

Thanksgiving came and I was invited to spend it in Washington. The next day, five of us who had been a close-knit film team, former colleagues who had gone our separate ways, went to a new restaurant. The kind where you wear jeans, drink expensive wine and the waiter describes the farm where the chickens were raised.

The next day, they went back to their lives and I returned to New York. Everyone wrote what a good time they had and named their favorite dishes. I was ready to say the charred brussels sprouts and cucumber ices except that what I kept thinking about was not the food but how they had all rearranged their plans to see me. Everyone at ease, even in the pauses. Sharing good news and bad. Forks reaching across the table. Familial reminders, “Don’t eat that, it’s too spicy for you.” How for a few hours I did not remember to be on my best behavior, I simply was.

I thanked everyone for coming and said how much it would mean to me to do it again.

I added, “I think you’re stuck with me.” A friend wrote back. “Stuck with you? Did you ever think you’re stuck with us?”

This renewed desire for deep attachments is a sign of wanting to rejoin life, isn’t it?

My friends, I am lucky to say, held on tightly even on the days I wanted to let go. When I could find no place for myself, they did. By what miracle that happens, I don’t know.

I’ll never stop thinking about my sister; missing her is a part of me now. At the same time, I’ve felt a growing warmth in the company of friends.

An act of kindness can bring me tears. A bit of teasing slides me off the chair. A favor asked, a fear confided. A future assumed. A late night call for help with a son’s homework. With each encounter a piece of story is laid down, like stones along a path.

These ties of friendship that hold us safely in their keep, that shape and share our memories, are among the hardest, most mysterious and most precious of all. Moment by moment, year by year we entrust ourselves to each other. In light of life’s fragility, friendship is our terra firma.