"It'll sort itself out"

Sometimes it does. It would be dishonest to pretend otherwise, and the habit survives partly because of the times it worked. A colleague was irritating and then got transferred. A friend went through a selfish patch and came out of it. You said nothing and the problem dissolved.

So it's worth being able to tell in advance which kind of thing you're holding. Here's a rough test, and it's my own and not drawn from research. Ask three questions about the thing.

Is it a one-off or a pattern? A friend who was short with you once, on a bad day, has given you nothing to discuss. One who's been short with you for three months has.

Does it depend on something that's about to change by itself? If the noisy neighbours move out next month, you can probably live with four more weekends. If nothing is scheduled to change, then it won't.

Has it stopped bothering you when you're not reminded of it? Things that are fading need no conversation. If you find yourself rehearsing, the thing is still live.

If the answers are pattern, nothing's changing and still rehearsing, then the thing won't sort itself out. You've already run that experiment. Every week you've waited has been a test of whether it would, and you have the results.

Now look at what an unraised pattern does while you wait. I can see four things, and again this is reasoning and not research.

It repeats, and each repetition adds to your file. In April you minded one Saturday. By August you mind twenty, and you remember most of them. The thing you'd have raised in April was small and recent. The one you're carrying now has a history, and the history will want to be heard.

It sets. Arrangements that go unchallenged become the way things are done. After five months, Saturday cycling is no longer something Sam started doing. It has become his Saturday. He's built plans and friendships on it. Asking him to change it in April would have been a small request about a new habit, and by August you're asking him to give up part of his life. His surprise will be genuine, too, because as far as he knows it's been fine with you all along.

Your silence gets read as agreement. People mostly assume that if something bothered you, you'd say. It's a reasonable assumption, and it's the one you make about them. Every week you don't mention the thing is a week in which the other person collects evidence that you're content.

And your feeling about it changes character. At the start you minded the thing. After months you mind that they haven't noticed you mind. A second grievance has been added to the first, and the second is often the more bitter. You now hold it against them that they didn't see it for themselves. Chapter 5 looks at whether that's fair.

Put together, this means that waiting isn't neutral. It's tempting to picture the conversation as sitting on a shelf, the same size whenever you choose to take it down. It doesn't keep. The thing you'd have raised in April was a small, fresh, specific request. By August you have a large and stale complaint with a history attached to it.

I should say something about things that can't be changed. Some of what we put off saying is about a fact and not a behaviour. "I was hurt that you didn't come to the funeral." Nothing can be done about it now. These don't grow in quite the same way, but they don't shrink either, and they do set. Distance in a friendship hardens much as an arrangement does. If a past event still comes between you and someone you want to stay close to, it passes the test above, and it's worth saying while the friendship is still warm enough to take it.