A scenario: A person, we'll call her "Ruth", is boarding a jet plane for some locale. Ruth is not old, but she does suffer from arthritis in a number of her joints, so whenever Ruth travels by air, she makes sure to purchase an aisle seat, which provides her with the greatest flexibility and ease of getting up and stretching during the flight, should the need arise.
Her fellow passengers board, including a husband who is sitting in the middle seat of Ruth's section and his wife, who is sitting in the aisle seat directly across from Ruth. The wife asks Ruth to switch places with the husband, with the husband taking the aisle seat and Ruth taking the middle seat, so the couple can 'sit together'. Ruth, citing her arthritis and the fact that she specifically paid for the aisle seat for specific reasons, refuses.
Was Ruth rude to refuse?