Rumors trickle out that things aren’t all kosher with Prince Empty. That his sparkle with Markle’s growing darkle.

Listen, many a regal togetherness has been a royal pain. Back aways nice Henry the VIII knocked off wives Anne Boleyn and Catherine Howard. And Catherine the Great didn’t have it so great. Marie Antoinette? Lost her crown plus her head. Also, how about Princess Diana?

Besides being crowned a Miss Ronkonkoma or the Bagel Queen, American females like Hope Cooke, Lee Radziwill, Rita Hayworth, Wallis Simpson craved titles. It beats marrying some manufacturer.

Grace on the throne

I recall my long back chat with Hollywood Oscar winner Grace Kelly who by then had osmosed into Her Serene Highness Princess Grace of Monaco.

Then almost newly unapproachable, we had a particular moment alone together when she felt slightly free speaking. Away from restrictions of her adopted homeland, we were in Iran. Both guests of His Majesty the Shah. Safe. Nobody listening. Just we two. Nobody monitoring her.

She said: “For a happy marriage, the man must head the household. My husband’s undisputed ruler of our house. His word is law.

“Despite occasional problems, I accept that. Of course, I try to lobby now and then.

“Marriage to a prince, a European head of state, is different. I’ve had to adapt to his way of doing things.

“One must get away to recharge the batteries. Breaks are needed for my husband and me to communicate. At home we always communicate via our secretaries. When I do catch him it’s to say there’s such-and-such’s party we must attend. And then we sit at a table with many people. It’s difficult.”

Realty check

Me: So is the palace homey? Ever feet up on a coffee table?

“We have our private apartment which I’ve done over in a modern manner. And I’ve tried to teach my children American ways. I don’t give them as much pocket money as their friends. I was brought up frugally, so I hold back many of their gifts.

“There have been stomach pains which you get from your children. Also — from them — prematurely gray hair.”

And, like us commoners, can two Serene Highnesses ever have a nice juicy fight?

“Of course there are . . . naturally . . . family disputes.”

So does a movie star turned international Highness holler in French or English?

A well-bred laugh, then, “We always . . . er . . . have our family disputes in English.”

Hollywood later beckoned and offered their old pro Grace Kelly — who’d had romances with Frank Sinatra, Oleg Cassini, Bing Crosby — a role in a movie. She wanted it. His Sereneness the husband said no. She didn’t go. Offered a play about her in Holland, she also couldn’t accept.

Frowning glory

Our chat was before Nicole Kidman faced Cannes headwinds starring in the film “Grace of Monaco.” The principality’s native-born royals, whose nostrils turned up higher than Pinocchio’s, deeply resented this portrayal of Hollywood’s Serene Highness Princess Grace of Philadelphia.

So, listen. Pay attention. See Meghan fight. She’s knocked off her father, swatted away her longtime best friend, expended body fluid on the whole of Great Britain, disappointed the company that hired her and has fought with reporters. Watch her scratch away Prince Empty. She’s hot to make her markle.