I am five foot two on a generous day, and for the eleven years Daniel and I were married, the passenger seat of his car was set for me. That sounds like a small thing. It is the kind of detail you stop noticing, the way you stop noticing the weight of your own wedding ring. The seat was tilted just so, slid forward so my feet reached the floor, lowered enough that I could see over the dashboard without craning. It was mine. It had always been mine.

Daniel loved that car more than he loved most people. It was a low, growling thing he had wanted since he was a teenager, and he had finally bought it the year his consulting work took off. He washed it on Sundays. He kept a microfiber cloth in the glovebox and would buff away my fingerprints from the window with a sigh that was half affection and half complaint. I used to tease him that the car was his real marriage and I was the affair.

That morning we were running late for brunch at his sister's. He was still inside hunting for his sunglasses, so I went ahead and got in. And I fell. There is no other word for it. I reached for the seat the way I reach for any familiar chair, and instead of meeting me halfway it dropped me. The seat had been pushed all the way back, so far that my legs dangled and my fingers couldn't reach the buckle. It had been lowered too, sunk down toward the floor pan. I sat there, half folded into the footwell, blinking at a windshield that suddenly seemed very far away.

My first thought was nothing dramatic. Maybe the valet at the restaurant last week. Maybe a mechanic. I reset the seat to my settings, slid forward, raised it, and by the time Daniel slid behind the wheel I had almost talked myself out of the strange cold feeling in my stomach.

Almost.

Because Daniel drove alone. That was the whole point of the car, the thing he said when I asked why we didn't just keep one sensible vehicle. It was his escape, his quiet, his commute. No mechanic had touched it in months; he did the oil himself. There had been no valet, no road trip, no reason on earth for that seat to be set for someone with legs at least eight inches longer than mine. Someone tall. Someone who reclined back and dropped low, the way you do when you are settling in for more than a quick ride.

I didn't say anything at brunch. I smiled at his sister, I passed the bread, and the whole time I was running numbers in my head like a woman possessed. The seat doesn't move itself. The car doesn't drive itself. A tall person sat where I sit, and recently, because Daniel is meticulous and would have reset it the moment he noticed, which meant he hadn't noticed, which meant whatever happened had happened in a hurry, late, in the dark, with his mind on something other than the seat.

That week I started paying attention to the small things I had trained myself to ignore. The late client dinners that ran past midnight. The phone that now lived face-down. The way he had started taking the car to "clear his head" on Thursday evenings, alone, supposedly. The microfiber cloth that no longer wiped my fingerprints away because there hadn't been any of my fingerprints to wipe.

I am not proud of what I did next. One Thursday I told him I was visiting my mother, and instead I sat in my own car two streets over from his office with a cold coffee and a worse feeling. At 7:40 his car pulled out. At 7:52 it stopped outside an apartment complex I didn't recognize. And at 7:53 a woman came down the steps, ducked her head, and folded herself into my seat. She was tall. She had to dip to get in, and she didn't touch a single control, because the seat already knew her.

I didn't cry. I had done all my crying in the footwell of that car a week earlier, before I even had a face to attach to it. I just watched the seat I had warmed for eleven years carry someone else into the evening, and I understood that the marriage had been over for longer than the seat had been wrong.

Daniel never confessed on his own. When I finally told him what I'd seen, his first instinct was to argue that no one had been in his car. He said it the way he'd said it the first time I'd mentioned the seat, automatic, almost bored. But you cannot argue with geometry. A car remembers the body that sits in it, and his car remembered her, all the way down to the inch.