Perhaps I am being cruel, but The Duke of Sussex may feel that being given marital advice by Donald Trump is akin to being given tips on childcare by King Herod.
The Sussexes have aroused the US president’s ire by putting out a video message urging Americans to vote in November.
Trump didn’t take long to respond, making little secret of his distaste for the Duchess of Sussex, before adding: “I wish a lot of luck to Harry, because he’s going to need it.”
His response was hardly surprising: Trump does tend to take things rather personally as followers of his Twitter feed will know only too well.
However, it says a lot about the febrile political atmosphere in the US that anodyne sentiments such as urging people to reject hate speech and exercise their constitutional right to vote can be politically and diplomatically explosive.
But with the presidential election, only weeks away, it is.
Rather wisely, Buckingham Palace went into damage limitation mode, stressing that the Duke was no longer a working member of the Royal Family and any comments he made were in a personal capacity.
Judging by the reaction, the horse had already bolted. Trump loyalist Corey Lewandowski was pretty pithy in his response.
“They made Britain great again by leaving, I hope they do the same for us.”
The reality is that the Sussexes are no longer part of the Royal Family and as an American citizen, the Duchess should be entitled to express her political preferences.
After all, she is hardly the first person from Tinsel Town to nail their colours to the mast. Lest we forget, one Hollywood star even became president.
On the other hand, even a nominal link to the Royal Family presents problems, especially at a time when the UK government is trying to negotiate a trade deal.
And Americans do not take especially kindly to outsiders telling them how to vote, as The Guardian discovered way back in 2004.
Rather unwisely, the paper launched what it described as “Operation Clark County” in which it asked its readers to send letters backing John Kerry against George Bush in the swing state of Ohio.
It did not go well and the backlash was spectacular. “Each email someone gets from some arrogant Brit telling us why to NOT to vote for George Bush is going to backfire, you stupid, yellow-toothed pansies,” was one of the more printable ripostes.
Other responses were not suitable for a family newspaper.
Whether the Sussexes’ intervention was a diplomatic error is still open to question.
But underpinning the whole controversy is a bigger issue - why encouraging people to register to vote should even be a matter of debate at all.
The sentiments expressed in the video were perfectly reasonable.
But it says something about Donald Trump’s supporters that they should take exception to a campaign to get as many people as possible to vote.
Call me old fashioned - I thought this is what democracy was all about.