Sounds plausible, yet regardless of the lead vocalist (Paul), the song sounds more like something Paul would write than John. John probably told Cyn that, but I think Paul wrote it for Jane and it is either mostly or all a Paul creation.
With a love like that, you know you should be glad, yeah, yeah, yeah!-- Beatles, 1963
If I seem to act unkind, it's only me, it's not my mind. -- George Harrison, 1966