Invasion of privacy? Oversharing? Welcome to the domain of the compulsive/professional blogger.
As for the reason for the switch... Let's not be too judgmental about the writer's boyfriend asking a stranger to swap seats to sit next to her. Sometimes people need to book seats at the last minute and there aren't two together. If the swap request entails like-for-like seats, e.g., "Would you mind sitting on the aisle one row back instead of on this aisle?" there's no shame in asking. It's only when a seat swapper offers a clearly inferior exchange that we FFs start to roll our eyes.