What waiting does to you
So far I've looked at what happens to the conversation and to the other person. This chapter is about the cost to you in the meantime. For some people it's the largest item of all.
An unsaid thing takes up room. You know this from the rehearsals. They arrive in the shower, on the drive to work and at night. Each one runs for a few minutes and leaves you slightly stirred up, as if you'd really had the argument. Over four months that's a lot of arguments. None of them happened, and you've still paid for them in mood and attention.
There's research on why unfinished business behaves this way. E.J. Masicampo and Roy Baumeister ran a series of studies on goals that people had left unfulfilled. Those who'd been reminded of an important task they hadn't done had more intrusive thoughts about it while trying to read something unrelated, and they did worse on a later task. The interesting part is what stopped the intrusions. The people who were freed from them hadn't finished the task. They'd made a specific plan for when and how they'd do it. Once a plan existed, the mind seemed willing to stop nagging.
Those were laboratory tasks and not strained marriages, so the carry-over is my step. But it matches what people commonly report. Once they've said, "Can we talk on Thursday?", much of the churning stops, before the conversation has even happened. The rehearsals had been your mind's way of keeping an open item in view. Once it has a date, your mind can leave it alone until then.
The second cost is to your enjoyment of the person. It's hard to delight in someone you're quietly angry with. You stop noticing what's good about them, because your attention is on the file. Small things they do start to look like more evidence. Sam leaves his cycling shoes in the hall and it isn't just shoes any more. People who carry an unsaid thing for long enough often find they've fallen out of fondness for the other person, and they take that to be a fact about the relationship. Often it's a fact about the file. When the thing is said and dealt with, a surprising amount of the fondness comes back.
The third is the effort of acting normal. You're running two versions of yourself. One says "Fine, have fun", and the other keeps a record. Keeping them apart takes some effort every day, and it makes you a little false with someone you'd like to be straight with. Most people find that tiring in a way they can't quite place.
The fourth is what it does to your view of yourself. Each time you resolve to say it and don't, you add a little to the belief that you're someone who can't. That belief then makes the next conversation harder to start. The habit feeds on its own record. Every hard conversation you do have goes on the record too, and counts the other way.
The last is that it spreads. The friend you haven't spoken to about the money becomes someone you see less. The colleague you haven't spoken to about the credit for the project becomes someone you avoid at lunch. You adjust your life around the unsaid thing, and the adjustments cost you more than the conversation would have. Some people lose friendships this way without a cross word ever being exchanged. They stop ringing, and nobody ever learns the reason.
I said in the preface that if this has been affecting your sleep and mood for weeks, it's worth telling a GP. I'll repeat that here. Most people who are carrying an unsaid thing are simply carrying an unsaid thing, and saying it is the cure. But prolonged poor sleep and low mood deserve attention in their own right, whatever's behind them.
Add these up and compare them with what the conversation costs. You'd have half an hour of real discomfort, and perhaps a difficult evening, and a few days of things being slightly tender between you. That's a real cost, and I won't pretend it's nothing. But you pay it once, and the costs of waiting are paid every day.