"It wasn't my fault"
Suppose someone drives into your parked car during the night and leaves no note. It's entirely their fault. You were asleep. All the same, the car with the crushed wing is yours, and if you want it repaired, you're the one who has to ring the garage.
Nobody finds that confusing when it's a car. You can be furious with the other driver and book the repair on the same morning. With a marriage, a childhood or a career, the two things run together, and "it wasn't my fault" starts to mean "so it isn't mine to deal with".
The belief underneath is a decent one. Whoever caused the damage should repair it. It's what we teach children, and it's the basis of a good deal of law. Where you can make it happen, you should, and chapter 5 comes back to that. The trouble starts when the person responsible won't repair it, or can't, or has died, or doesn't accept that they did anything. Then the principle gives you nothing to do. You're left holding a rule that only the other person can carry out.
It helps to split one question into two. Whose fault was it? Whose move is it? The first looks backward at what happened. The second looks forward at what happens now. They have different answers more often than we'd like.
This split has some history in psychology. In 1982 Philip Brickman and his colleagues published a paper on how people think about helping and coping. They argued that responsibility for a problem and responsibility for its solution are separate. You can hold someone to account for one without the other. They set out the four possible combinations, and they favoured the one in which a person isn't blamed for the problem and is still treated as the one in charge of the solution. Their reason was that it lets someone accept help without shame and keeps their life in their own hands. The paper is a framework and didn't test anything, so take it as a useful way of cutting things up.
I think people resist this because making the move feels like pleading guilty. If I'm the one sorting out the debt, it looks as though I accept the debt was mine. If I'm the one who rings, it looks as though the silence was my doing. English doesn't help. "Take responsibility" means both "admit you were to blame" and "deal with it". People who told you to take responsibility often meant the first, and that's why it grated. I only ever mean the second.
Some readers have the opposite trouble, and swing between "it's all their fault" and "it's all mine, I'm the sort of person this happens to". The second is no improvement. In 1979 the psychologist Ronnie Janoff-Bulman separated blaming your own behaviour, which you can change, from blaming your character, which you can't. In her study of students, the depressed ones did more of the second kind. The question "whose move is it?" needs no verdict on your character at all. It doesn't even need the fault question settled. Two people can disagree for ever about who wrecked a marriage, and the envelope from the bank can still be opened this evening.
The honest objection is that this is unfair. You didn't break it, and now you're doing the work of mending it. Yes. It is unfair, and I'm not going to argue that it's fair underneath if you look at it properly. You're paying a cost that belongs to someone else. But look at the choice that's actually open to you. It isn't between a fair outcome and an unfair one. It's between an unfair situation with the damage repaired and an unfair situation with the damage still there. The other person's bad behaviour took the fair options away.
You also don't have to choose between the two questions. You can ring the garage and report the driver to the police on the same day. Pursuing the fault and making your own move can run side by side. The habit is what happens when the first one stalls and you let the second stall with it.
Go back to your written grievance and put the two questions underneath it. Answer them separately. For the fault question, write whatever's true, and it may well be "entirely theirs". For the move question, list anything you could do, however small, and leave out whether you should have to.