My wife has a habit of leaving tiny notes around the house: "buy milk," "call dentist," "don't forget charger." Sometimes there are stranger ones like "you handled yesterday well" or "stop assuming everyone is angry with you." I know those are meant only for herself, and I probably shouldn't read them.
A few months ago, I found one inside a kitchen cabinet that said, "Tell him you're scared about money." She never did tell me. That night I went through our finances and realized she had been quietly panicking over something we could actually manage. I started a conversation without mentioning the note. I still feel guilty for reading it, but I'm also glad I did.