I don't know if this will help. I can only tell you about my personal experiences. Do you ask your wife why often? It seems she uses the word why when talking to you. The question why is often perceived as a challenge. It's a communication misinterpretation. For many people struggling with trauma and anger, being asked why can cause conflict, as if whatever is "wrong" with us is causing all manner of problems. The conflict can put us on automatic defense for the long term.
My ptsd therapist taught me to not ask myself why when I struggled to understand my anger. She taught me to ask myself "what reason I feel anger" instead. The psychological difference between why (aka constantly blaming myself) and what reason (aka discovering what triggered my anger and ptsd) has been a major step in my own healing.
I don't think you have anything to lose by asking the reason for something instead of asking why. Isn't that what you want to know anyway... the reason?
I hope you and your family can find peace and happiness.