Later on that same ride...

Two people in the next row start to argue, low-voiced, but intense. One says something sharp. The other goes quiet, jaw set, eyes forward.
You weren’t trying to listen, but now you can’t unhear it. One of them notices you glanced their way. Just once. Nothing more. The silence stretches. They might think you’re choosing a side.

What do you do, if anything?
And what decides that for you?