Questions that start with “why” are sly old dogs;  especially if they are directly addressed to someone else. “Why were you there?”, “Why did you do it this way?”, “Why haven´t  you called?” etc. These questions pretend to want an answer for a better understanding. But they usually act as hidden accusations and lead to anger and justifications. If it really is all about understanding, one of the following formulations is more targeted and less ambiguous: “What were your reasons to go there?”, “How come you have made it this way?” Or “What was it that made you not call?”

If you want to avoid such misunderstandings, hidden accusations and anger, I suggest as a first step, the following observation:
What´s your inner reaction when you are asked a why-question?