In an interview with David Sheff in 1980, Lennon explained how McCartney’s recording of Why Don’t We Do It In The Road irked him.
McCartney apparently recorded the entire song in secret, on his own, by performing all of the drums, guitars, piano, and singing by himself.
Lennon explained: “That’s Paul. He even recorded it by himself in another room. That’s how it was getting in those days.”
It is obvious that the band were having problems at the time, according to Lennon’s remark.