I passed by the only other person in the aisle, a young blonde woman in an off-white suit looking at garbage bags, and as I approached Sarah I waited to see when she might take her eyes off the various spaghetti sauces to check that her purse was still where she’d left it in the cart.

I was doing a slow burn.

It was clear that I was completely wasting my time trying to get anyone in my household to exercise even the most basic level of common sense. I had, I knew, become something of a nag where Sarah and her purse were concerned. There had been stories on the news. That woman with the lottery ticket. That other woman, who’d lost the pictures of her sister’s wedding. There were some things you just didn’t do, and leaving your purse unattended in a busy grocery store was one of them.

It appeared, from where I was standing, that the purse wasn’t even snapped shut at the top. Wasn’t that thoughtful. A thief didn’t even have to go to the trouble of running off with her purse, he could just peek inside and help himself to what he wanted.

What was she thinking? You need your hands free when you’re shopping, she’d tell me.

You might think that a woman who spends her day sending journalists to court to write about men who’ve cut their girlfriends up into bits and distributed them like Wal-Mart flyers would be aware that there are a lot of not-nice people out there. People who might walk off with a woman’s purse while she is debating the merits of onion-and-garlic versus three-cheese pasta sauce.

It was only a matter of time before someone walked off with that purse. So I had a choice to make. Would it be a stranger, or would it be me?

Don’t do it, my conscience said. Don’t do it.

The incident over the keys, and my hiding her car, seemed largely forgotten. We were talking to each other, Sarah and I. Things had been fairly remarkable between the sheets the last week or so, and I had performed, if I may say so, spectacularly. There was peace in our time.

And yet.

I could stand by the cart, guard the purse while Sarah perused sauce. But what about next time, when I wasn’t with her? While she had her back turned for only a minute, someone would quietly loop his hand around the strap and tuck that purse inside his jacket.

I had the power to do something instructive. Something helpful.

I sidled past the cart, empty but for a package of low-fat cookies. Was Sarah about to make us all start watching our calories? I came up alongside her and said, “You almost done?”