Watching and doing nothing is still a choice. It just has no fingerprints.

Standing by feels neutral because it leaves nothing behind that anyone can point at. It is still a decision, made in real time, with a real effect on how the moment goes. Most bystanders are not indifferent; they are waiting for someone else to move first, and everyone present is running the same arithmetic. That is how nothing happens.

You do not have to confront anyone to break the pattern. Say the person’s name, ask a question, change the subject, go stand beside them. Small interruptions work, and they are usually enough for someone else to join in.