Here is the scenario:
You step on a semi-crowded public-transportation bus. Some people are standing but you manage to find a seat! You sit next to some one in a two-person seat and enjoy your ride. As you go along the route many people debark and the crowd thins out. You notice that a few two-seater spaces are now completely empty.
Do you get up and take an empty seat, allowing both you and your seatmate to have two places to your selves? Or is that rude, and sending the message that you don’t like sitting next to the person, possibly causing them to think they are hideous, or too wide, or emitting a disturbing odour? What’s the etiquette here?