“ LENNON:”All My Loving” is Paul, I regret to say. Ha ha ha.
LENNON: Because it’s a damn good piece of work. … But I play a pretty mean guitar in back.”
The complicated rhythm guitar is probably the reason that John left the deep singing part (in the last verse) to George, he simply couldn’t do both.
Cynthia Lennon believed John wrote it for her, but in fact Paul (the writer) probably had Jane Archer in mind when he wrote the lyrics.
We should also pay attention to Ringo’s great drumming, it has a very distinct and difficult to copy, latin style. It add a sophisticated rhythm to a song that without it would much more ordinary pop/rock, this is evident on the Live at the BBC album were he plays an ordinary 4/4 rhythm. It gets a more rock’n roll feel but loses a bit of it’s uniqueness, I think.