Swap “why would you do that” for “what happened?” and watch the other person stop bracing for impact.

One question asks for a defence, the other asks for an account. Starting with why puts the person on trial before you have any facts, and people under accusation supply justifications instead of information. Asking what happened gets you the sequence of events, which is what you actually needed. Same curiosity, entirely different result.

Use it the next time something has gone wrong and you want to understand it. Ask what happened, then stay quiet through the whole answer. You can still be unhappy afterward, but you will be unhappy about something accurate.