"They already know"

This is the belief that empties most of the drawer before anything else gets a look in. Your partner knows you think they handled it well. Of course they do. You've been together eleven years. Your colleague knows the slides were good, because the meeting went well. Your dad knows you can see him with the children. It's obvious. Saying it would be like announcing the weather.

I'd ask what they know it from. What your partner has is eleven years of what you've said, and what you've said, if you're reading this, is mostly not this. They have the sigh at the bins and the question about the car. They don't have the sentence you thought on the stairs, because it was thought on the stairs. Your colleague has a meeting that went well, which could mean the slides were good or that nobody was listening. An earlier book, They can't read your mind, is about expecting the people close to you to know what you need without being told. The same mistake works the other way. They can't read what you admire off you either.

Xuan Zhao and Nicholas Epley, two psychologists who study how people misjudge each other, ran nine experiments on this and published them in 2021. They had people write a genuine compliment for someone and then predict how the recipient would feel, how happy and how awkward. Then the compliment was delivered and the recipient reported how they actually felt. The people writing the compliments consistently underestimated how good it would make the other person feel. If the recipients had already known, a compliment would have told them nothing and moved them very little. It moved them more than the writers thought it would.

I read that as the "they already know" belief tested and failed, and I'll say what I'm adding to it. If your partner knew, in full, what you thought on the stairs, hearing it would be mildly pleasant at best. The reason it lands harder than you expect is that they didn't have it. They had the thought version, which is nothing, because the thought version lives in your head and nowhere else.

Here's the plain form. People know what's been said to them. They don't know what's been thought about them, however obvious it is from inside your head, and the more years you've spent not saying it, the more sure they can be that it isn't there.