I don't know why the preposition "on" should be used here. What about "about"?

Native speaker’s answer
Rebecca
The use of the preposition "on" is quite unnatural here. The correct preposition here is definitely "about". As this is the lyrics to a song, the most logical reason for Adele choosing the word "on" instead of "about" is probably because it is shorter and works better with the flow of the song. However, when we talk about watching a show about something or reading a book/article about something, you can use "on" and "about" interchangeably as they have the same meaning. Ex: I read a book about birds. / I read a book on birds. Ex: I watched a documentary about the Civil War. / I watched a documentary on the Civil War.