Julie Montagu, an American viscountess, knows that marrying into British aristocracy isn’t as glamorous as it sounds.

The 47-year-old Illinois native moved to the U.K. 16 years ago when she said "I do" to Luke Timothy Charles Montagu, Viscount Hinchingbrooke, the son of the 11th Earl of Sandwich. She currently helps her husband run the family estate in Dorset – the 16th-century Mapperton House & Gardens.

She believed American actress Meghan Markle struggled to understand that her "duty was to the queen" when she married Britain’s Prince Harry in 2018.

"You can’t really be anything you want to be or do anything you want to do or say anything you want to say," she revealed in the U.K. documentary "Meghan at 40: The Climb to Power," as quoted by the DailyMail on Friday.

BEFORE PRINCE HARRY, EDWARD VIII WROTE HIS OWN TELL-ALL AFTER MARRYING AMERICAN DIVORCÉE WALLIS SIMPSON

Meghan Markle Queen Elizabeth

Queen Elizabeth II and Meghan, Duchess of Sussex watch the RAF flypast on the balcony of Buckingham Palace, as members of the Royal Family attend events to mark the centenary of the RAF on July 10, 2018 in London, England.   (Photo by Chris Jackson/Getty Images)

The Duchess of Sussex turns 40 on Aug. 4.

"Your duty is to the queen and that’s very difficult for someone like Meghan," shared Montagu. "To switch off that American dream off and accept ‘now you have to do what we say’ is difficult. It’s difficult to have love and duty work simultaneously and together and that’s what Harry and Meghan wanted in negotiations with the queen, this synergy, that they can make work, but the queen said no."

MEGHAN MARKLE'S ESTRANGED FATHER THOMAS REVEALS MOMENT SHE DISCOVERED STARDOM: 'DADDY, I WANT TO BE FAMOUS'

According to the outlet, the documentary is alleging that Markle and Harry, 36, gave their "truth bomb" to Oprah Winfrey in March because they "expected an apology" from the royal family.

"I think she felt it was an opportunity for her to not only share it with the world, but she hoped the royal family was actually listening," said Montagu.

Julie Montagu, an Illinois native moved to the U.K. 16 years ago when she married Luke Timothy Charles Montagu, Viscount Hinchingbrooke, the son of the 11th Earl of Sandwich. 

Julie Montagu, an Illinois native moved to the U.K. 16 years ago when she married Luke Timothy Charles Montagu, Viscount Hinchingbrooke, the son of the 11th Earl of Sandwich.  (Photo by Ki Price/WireImage/Getty Images)

Back in 2020, Montagu told Fox News she wasn’t surprised that Markle moved back to the U.S.

"She was getting such really relentless negative press from the British tabloid press," she said t the time. "It doesn't surprise me at all. I think they had enough. And we saw what happened to Princess Diana. And I think the last thing that Harry wanted to happen was the exact same thing that happened to his mother. So, I think that they really gave it a good go. I mean, I was there, I read all the articles."

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

She also wasn’t surprised that Harry would leave behind his home country for a new life in America.

"I think that Harry was always the rebel, wasn't he?" she said. "He probably is preferring that life. He's not hounded by the press. He's been hounded his entire life. He's finally being, for the most part, being left alone and he gets to live this laid-back life. They just do what they want to do."

Britain’s Prince Harry and his wife Meghan ride a horse-drawn carriage after their wedding ceremony at St George’s Chapel in Windsor Castle in Windsor, Britain, May 19, 2018. Benoit Tessier: "After installing my equipment, I had a long wait before seeing the couple. After six hours, they finally passed by. Meghan seemed very excited." REUTERS/Benoit Tessier/File photo SEARCH "WEDDING PHOTOGRAPHS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY - RC1B0322B330

Meghan Markle became the Duchess of Sussex when she married Britain's Prince Harry in May 2018. (Reuters)

The Duke and Duchess of Sussex’s departures from royal duties began in 2020 over what they described as the British media’s intrusions and racist attitudes towards the former "Suits" star. The family now resides in the coastal city of Montecito, Calif.

In the wake of quitting royal duties, they gave an explosive TV interview Winfrey, 67, in which the couple described painful comments about how dark their son Archie’s skin might be before his birth. The duchess talked about the intense isolation she felt inside the royal family that led her to contemplate suicide.

CLICK HERE TO GET THE FOX NEWS APP

Buckingham Palace said the allegations of racism made by the couple were "concerning" and would be addressed privately.

Winfrey and Harry collaborated on the Apple TV+ mental-health series "The Me You Can’t See."

Meghan Markle Prince Harry

The Duke and Duchess of Sussex currently reside in California with their two children. (AP)

On June 4, the couple welcomed their second child, a daughter named Lilibet "Lili" Diana Mountbatten-Windsor. The child is eighth in line to the British throne.

The name pays tribute to both Harry’s grandmother, Queen Elizabeth II, whose family nickname is Lilibet, and his late mother Diana.

The Associated Press contributed to this report.