Don’t begin your question with “why?”
Here’s another strategy to keep the other person from getting defensive, so you can both remain in dialogue.
When you begin your question with “Why” as in “Why did you do that?” what happens?
It can make people feel like you’re questioning their autonomy.
Marshall Rosenberg, the founder of Nonviolent Communication (NVC) calls this limiting language, which disconnects people, often leading to conflict, misunderstanding, and a personal disconnection from our own feelings and needs
As an alternative, you can begin your phrase with “what” or “how” as in:
How did this happen?
What led to this?
Another alternative is to put yourself in the position of the learner:
Help me understand
Walk me through your thought process
This is the opposite of limiting language because it connects and keeps you focused on mutual objectives.