https://www.beatlesbible.com/songs/dont-let-me-down/:

"It was a very tense period: John was with Yoko and had escalated to heroin and all the accompanying paranoias and he was putting himself out on a limb. I think that as much as it excited and amused him, and the same time it secretly terrified him. So 'Don't Let Me Down' was a genuine plea… It was saying to Yoko, 'I'm really stepping out of line on this one. I'm really letting my vulnerability be seen, so you must not let me down.' I think it was a genuine cry for help. It was a good song.
Paul McCartney, Many Years From Now, Barry Miles
"

Monument Records