Yes, I heard that from the horse’s mouth. Linda McCartney said that on some TV show, maybe Regis and Kathie Lee. When would he have had the opportunity to cheat?
Look at JFK. When you have money and “yes men” around you, you can do anything. But I think Paul had to be more normal than the rest because he came from a more stable family.
But remember JFK - he used to hide in closets in the WH with his women. And there was no way the Beatles had anywhere near a normal existence.