"It's their worry too, I'm protecting them"

Some worries have a co-owner. The bank letter is about the joint account. The quiet marriage is your partner's marriage too. The son is their son. And here the burden belief has its strongest form, which is that telling wouldn't be sharing a worry, it would be creating one, in the person it's about, who's happy now and wouldn't be.

Two things. The first is that "protecting them" is a decision made about their life without consulting them. You've decided that your partner is better off not knowing about the account they share, or the quiet they're living in, or the change in their son. That might be true. It might not. What's certain is that it's not yours to decide alone, because the thing is theirs as much as yours, and deciding for another adult what they can bear is a kind of managing that most people, told about it later, don't thank you for.

The second is that the co-owner isn't happy now. They're living with a partner who's been quiet and tired and moving money around and saying "fine" for a month. They don't know what's wrong. They know something is. The not-knowing is its own worry, and it's often worse than the thing, because it has no edges and no Thursday and no way to help. You haven't spared them a worry. You've given them a different one and taken away the means of doing anything about it.

There's a fairness point too. A worry about the joint account, carried by one person, is one person doing the arithmetic at three in the morning while the other sleeps. Telling the co-owner doesn't double the worry. It halves the night. Two people looking at a letter is a different experience from one, and the difference isn't only that it's shared. It's that two people looking at a letter is how letters get answered.

The co-owner is the first person to tell, before the friend, before the sister. Chapter 20 says so and says how. If the thing is between you, if the quiet marriage is the worry and the partner is the co-owner and also the cause, that's a different conversation, and an earlier book in this series is about raising a difficulty with the person it's about. The telling in this book is to a third person, and the co-owner of the marriage worry might be a friend rather than the partner. But for the account and the son, the partner is the co-owner, and protecting them by silence isn't protection.