A memory can feel private even when hundreds of people were present.

Shared events are experienced one person at a time. Everyone in the room heard the same music or the same announcement, and each of them was standing inside a different life while it happened, attaching it to different worries and different people. Your version of it is genuinely yours, not because you were alone but because the meaning was assembled privately.

This is worth remembering when you assume a common experience gave everyone the same thing. Ask someone who was there what it meant to them rather than confirming that they were present. The answer is usually further from yours than you would expect.