Sometimes closure is realizing the explanation would not change the evidence.

Sometimes you realize that even a full explanation would not change what you saw happen. The pattern is documented, the behavior was repeated, and understanding the reasons behind it would not alter a single one of those facts. That realization is the closure you were waiting to be handed.

Write down what you actually observed, separate from what you were told. Then notice how little the missing explanation would move it. The account is already complete enough to act on.