Someone doesn't reply, or uses a short tone, or forgets a thing they promised — and within seconds you have a whole story about what it means. Usually not a generous one.
The mind hates a blank, so it fills one. It reaches for the explanation that fits your fears, not the facts. Then you respond to the story you invented, as if it were the truth.
Most of the time you'll never know the real reason. But you get to choose which version you act on. The generous reading is rarely less accurate — and it costs you far less to carry.