It isn’t a love song. It is about Paul McCartney's mother's death.
I found out from the horse’s mouth, so to speak, from this interview with Paul McCartney airing on NPR this week, in honour of the 50th anniversary of The Beatles’ conquest of America.
In the interview, Paul talks about how he lost his mother as a teenager. John Lennon also lost his mother at about the same age, and that shared experience of loss was a deep bond John and Paul shared. However, as working class lads from the North, they couldn’t talk about it. It just wasn’t done. It was put to Paul much later in life that Yesterday might be about his feelings when his mother died, and it dawned on Paul that that was probably true.
The song sounds different now, now that I know this interpretation. Still a great song. But different.
