Wallis Simpson allegedly told friends that all the partying & hob-nobbing eventually became empty & shallow as the Duke of Windsor eventually realized that none of those people were really his friends. They just invited him to parties & such to be able to tell everyone they have a Duke coming to their parties.
I hypothesize Hitler probably played the Duke in the same way, only he couldn't see it. Hitler was supposedly really a very charismatic person at first. That was how he was able to rise up & get so many people behind him before later using force by his soldiers. He probably cozied up to the Duke, flattering his ego, saying how much power the two of them will have once David is returned to the throne - with
real power, not just being a talking figurehead, and they can rule Europe & the world together.
Kind of interesting to think how many details, had they gone the other way, could have ended the war and our way of life so differently.
Like if we hadn't created the atomic bomb first, if Indiana Jones hadn't found the Ark of the Covenant first.