When we get unexpected results or unintended consequences to our actions we can spend a lot of time and effort in trying to answer the question why. Often there is no real single undeniable why for us to discover there is instead a whole pile of little whys that have ganged up to give us our result.
We presumably do this in order to prevent it from happening again. It never will because we will never have the same set of circumstances, people, events, and opportunities again. That's right never.
The better question to ask is where were we blind either through ignorance or from us ignoring what didn't want to know even when it was staring us in the face. In this way we work on the thing that we can change rather than things beyond our control and that is ourselves.
Wisdom is learning the lessons about ourselves and others and applying them better. So perhaps we needn't look so hard for the why outside of ourselves and make better decisions and better actions until we get it right.