When my father came home to New Rochelle from his job in Manhattan, he was usually tired and grouchy. But on some days, inside his beaten-up briefcase, nestled among yellow pads, would be large bags of candy, usually chocolate, for my brothers and me. He had visited a Duane Reade during his lunch hour and loaded up on candy to assuage his stress, or so I imagined. There are worse vices.

Duane Reade didn’t exist in our suburb, so as a child I knew it not as a drugstore chain but a magical candy land — and my father’s happy place.

Years later, when I moved to New York City for college, I learned firsthand the joys of perusing the aisles of Duane Reade: piles of pastel Easter candy as an early sign of spring, toothbrushes behind plexiglass as a sign of shoplifters, nail polish colors I looked at but never purchased, cheap earrings that elicited compliments to which I proudly responded, “They’re from Duane Reade!”

Later still, I learned how the store’s name came from its first location, at the intersection of Duane Street and Reade Street in downtown Manhattan.

The store sells all of life’s mundane items, which in the end get trashed, recycled or flushed. Items that are nothing but also everything: lint rollers, deodorant, greeting cards, magazines, school supplies, vitamins.

That time I had a headache, or a sore throat, or that other time when my husband’s allergies flared up after we rode in a cab through Central Park when the pink double blossom cherry trees were in bloom, him with his head out the window like a golden retriever glowing with joy, but a person. My person.

My husband and I separated in 2016. We didn’t have children or own property or have much money. Our marriage was glorious until it wasn’t. In the end, we weren’t even sharing meals. But one thing that has lingered is our shared Duane Reade rewards account, the kind that gives you discounts and points. It’s one of those artifacts so minor, so inconsequential, that I never think about the fact that we still share it until seconds before I pay. Then, boom, beep, and the receipts are emailed to me.

He now shops at his Duane Reade near where he lives, not at our Duane Reade, because there is no longer any “our” (except for our shared rewards card). I see from his itemized receipts that he bought three rolls of Christmas tissue to wrap gifts (not for me), teeth whitening products (for smiling at someone else), hair taming cream (for his unruly locks), and he was charged the five-cent shopping bag fee (because evidently he forgot his).

My therapist would say I should close the account, but I stopped seeing her a few years ago. My ex-husband and I are still in touch, and when I reminded him of our shared account, he said he knows I love Duane Reade and gave me permission to use his points (and even gave me permission to write about all this).

It is the most minor transactional connection to someone, yet it is also so intimate. Maybe it’s our last thread of control or codependence or manipulation. But on an uncomplicated level, it’s a kind of generosity that lives to see another fluorescent-lit day.

Recently, I received a Duane Reade receipt of his that had women’s hair dye on it. Dark chestnut brown. My color. He is a dirty blonde. What was he doing? Was it for his new girlfriend? Or was he dying his own hair?

I ruminated about this for so long that it became unhealthy. Finally, I asked him.

“Oh, it was for me,” he said. A cosplay thing. The exact shade he needed for his costume to be accurate. He always was an artist at heart. Professionally, he designs and builds scenery for retail, fashion and films and is passionate about his work. I loved that about him, yet it’s also part of what ended us.

And now my local Duane Reade is coming to an end too, closing permanently. The second to last time I was there a couple of months ago, I braced myself before entering, but it wasn’t as cleared out as I expected. And none of the candy was on clearance yet. The Valentine’s cards were overflowing, like feathery, sequined, oxygenated blood still pulsing through veins.

As I waited to pay, six feet behind the person ahead of me, a man appeared with his arms filled with mops and brooms. Crouched and gray-haired, he fled outside mumbling — and without paying. He wasn’t even fast.

The people who worked there did nothing; I assume they had been told not to put themselves at risk in these situations. I also did nothing.

I idly wondered what kind of big cleaning project he might be doing until the woman who worked there said loudly, in an exhausted and resigned tone, “He’s going to sell them.”

I am sad to see the store go. An optimistic and unsentimental neighbor of mine is already hoping a Trader Joe’s will move in. Living in New York City constantly reminds us that, for better and worse, change is afoot. And this rapid turnover forces us forward — to an imaginary future that is supposedly better than our present.

Better not to look back. Better not to dwell on the millions of hearts that have thumped and broken on this very patch of pavement. Right?

As Gloria Steinem once said at a lecture I attended nearly 17 years ago in response to an audience member who was lamenting the long-gone cultural and political vitality of the 1960s: “Nostalgia can be disempowering.”

This statement stopped me in my tracks. As a certified sentimental sap, raised by parents whose only good days were the old ones, I had never thought of glorifying the past as potentially problematic. But of course it can be.

Then, in 2014, three researchers won a Nobel Prize for their discovery of “place cells” and “grid cells,” neurons in the brain’s hippocampus and entorhinal cortex that help create a spatial map of the world and generate a sense of direction. Every time a rat walked into a corner of the maze that it knew well, the same group of neurons became activated and started firing electrical signals. These act as a kind of GPS system and help organize memories about specific locations.

Humans have place cells and grid cells, too. Which makes me wonder if, when the Duane Reade is no longer on my corner, will my “place cells” for it remain, smoldering forever? Maybe my place cells will betray my inner Gloria Steinem, pulling me back to the past for a few precious milliseconds. But probably we can only credit these cells for delivering a neutral message of “You are here,” while the bittersweet “I remember when — ” comes from somewhere else entirely.

My ex-husband is unlike my father in many ways. He is a cheerful person, quick to laugh, and warm. But my father always managed to come home on time, and in this respect my ex was also different: He almost never made it home on time, and on many nights, he never came home at all.

He’d had a complicated childhood and was especially close to his brother, with whom he works. Friends suggested he was cheating. But I knew he was just trapped in an all-night flurry of anxiety about clients, medium-density fiberboard and his brother’s needs.

And anyway, I now know that it didn’t really matter why he didn’t come home, only that he didn’t.

Our daily life unraveled. And all the consumables that mark the passage of regular days were no longer shared. He didn’t know what we had in the refrigerator, nor did he know the status of our toilet paper, Q-tips or hair traps for our sinks. These daily necessities failed to anchor him to our home; it was more like he was just passing through.

When I went back to my Duane Reade for the final time, the person ringing me up told me I had five dollars’ worth of points and asked me if I wanted to use them.

“No,” I said. I paid and walked out into the snowy city with two bars of soap, some paper towels, and a lump in my throat for which there is no medicine.

I know that until I close our joint rewards account, I will continue to receive my ex-husband’s receipts, like love letters from the landfill. And maybe a specific cluster of neurons for the life we once shared will fire for the rest of my days. But now that my local Duane Reade is gone, I no longer need his points.

Julia Zichello, who lives in New York City, is an assistant professor of biology who studies evolution.

Modern Love can be reached at modernlove@nytimes.com.

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