You don't have to win this one
What it does to them
Winning is quiet for the winner and loud for the other person, so it's worth a chapter from their side.
Living with someone who has to be right means learning what happens when you're wrong, which is a demonstration. So you check before you speak. You hedge. You say "I think it was Wednesday, but I might be wrong", and then when you were right you don't say so, because that would start another one. Over time you speak less about facts, because facts are where the demonstrations happen, and you speak more about nothing, because nothing is safe.
The concessions are private. "Whatever" isn't agreement. It's a door closed on an argument that will be reopened, in your head, on the sofa, while they're pleased with the calendar. You go over it. You know the recycling was Tuesday that week. You don't say it. You add it to a list that you'd deny keeping, and the list is long, and it's about them.
Christensen and Heavey's withdrawing partner is the one in this chapter. Withdrawing looks, from the other side, like giving in, and feels, from the inside, like being pushed out. The withdrawer isn't persuaded. They're conserving. And a person who's conserved for twenty years has a lot conserved, and none of it is affection.
There's the child. A child at that table learns one of two things. Either they learn to argue, because that's how you get to be right in this house, and they'll bring it to their own table. Or they learn to go quiet, like the parent who does, because quiet is how you survive a demonstration. Both are lessons about what a disagreement is, and both are wrong, and both were taught by a calendar.
There's the hedging, which becomes a way of speaking. "I might be wrong but." "I think, though you'd know better." Over years, a person who lives with the calendar develops a manner of qualifying everything they say, and carries it out of the house, to work, to friends, where it reads as a lack of confidence, and it isn't. It's a habit learned at a table where unqualified statements were expensive.
And there's what they stop sharing. The story about what their mother said at Christmas wasn't a claim to be tested. It was a thing they wanted to tell you. When it became a dispute about Boxing Day, they learned that telling you things is a risk, and the next thing their mother says, you won't hear about, and you'll wonder why they never tell you anything.
None of this is what you intend. You intend to be accurate. But from their side, accuracy arrives as being corrected, in front of the children, about a date, by the person who's meant to be on their side. That's what winning is, in the other chair.