I have long conversations in my head. Sometimes they’re with other people, but not always. Often, they’re with my husband. Sometimes I talk to him more inside my head than face to face – although I am sometimes talking to him inside my head when we are face to face. He is glad for the inside-my-head aspect of our conversations, or at least he would be if he had to listen to all of it.

My shampoo is the latest thing we’ve been discussing in my head. My husband ran out of his shampoo and started using mine. I know this because it is disappearing at an alarming rate. I don’t even have to make those little lines on the bottle to mark the last known volume to see that it is disappearing faster than normal.

Full disclosure: I spend more on personal care products than I should. But I hardly use them. They last right up to the expiration date with me. I am careful, judicious, and cheap. I don’t know why anyone wouldn’t be. I mean, you wouldn’t use your eye cream as a body lotion, would you? Of course not, unless it’s not yours and it’s right there and you need body lotion and no one will notice.

So I stand in my shower and eye the bottle, which is emptier than I left it. He’s used my shampoo, I think. Will he buy more when it is done? Or will he move onto someone else’s shampoo? If he moves on to someone else’s and I buy myself another bottle of salon shampoo will he come back and empty it again? What did he get on his report card, on the line that says “respects other people’s stuff?”

This is when I call the entire family to the dining room table inside my head for a talk, because it’s now a life lesson. When these kids leave home, I plan for them to be fully functioning humans who are a delight to live and work with. Read: people who don’t use their roommates’ shampoos.

I start to doubt myself at this point. People don’t use each other’s personal care products, unless possibly they do when they’re married. What is the rule for this? I’ve had siblings and roommates, but I was never called to a dining room table family discussion about the politics of using each others personal care items in marriage.

I was practically 70 when I met my husband. I realize this is a biological miracle since we had two children after we met and married, so 70 may be more of a state of mind than a chronological fact. I had lived on my own a long time. I had matching china, tools, and a dust ruffle.

I know that I am picky about things not worth having outside-my-head conversations about, and have managed some workarounds. I bought him his own toothpaste and put it with his toothbrush in his own tooth care cup so he will stop leaving the cap off my toothpaste and squishing it from the middle. I bought us his and hers razors. His is a bright color he can’t help but notice and grab, while mine blends cannily into the shower basket.

I don’t mind if he raids my cast-offs from the bathroom closet. The No Frizz bottle that is of no use to me since my hair – which once rivaled Chia Pets – is inexplicably thinning. He is welcome to use it on his full head of Kennedy hair. Innumerable bottles and jars of lotion, relegated to the closet, are all his.

When I first noticed my shampoo decreasing I took evasive action. I put it in the corner of the shower no one ever looks in. I accidentally took it with me and kept it in my bathrobe pocket. I put the family shampoo front and center. And then I felt like a freak and put mine back where it was.

I will buy a new bottle when the time comes, I thought. This is not a big deal.

But seriously, is he using it as body wash? I think, noting that the level has dropped below Rosemary Mint and is approaching the ingredient list.

As I toweled off it occurred to me that not only is the level dropping, he smells like me.

When the kids were babies I realized I frequently rubbed my face on theirs, like a mother cat marking her young. I have stopped because they’re practically driving now and are taller than me, but the impulse is still there. What is so wrong about scent-marking your family so it’s evident that we are a unit? I have never managed to do this with my husband because marking your spouse seems like something out of a movie, probably starring Glenn Close. It’s creepy and possessive and I’d never get away with it. Unless, of course, he did it himself. Using my shampoo as hair and body wash. I can’t believe I didn’t think of this sooner. I am a genius.

“Hi,” I say, rubbing my face against his for good measure. “You smell nice.”

I’m so glad we had this talk.