Queen Elizabeth II already has enough problems she carries on her shoulders, but Her Majesty reportedly suffered privately because of three of her four children.

Since taking over the throne, Queen Elizabeth II has been known for being stoic regardless of the issue that bombards the royal family. She showed the same attitude when three of her children - Prince Charles, Prince Andrew, and Princess Anne - faced divorces in their marriages in the 1990s.

Despite that, an upcoming biography revealed that she acted differently behind the scenes.

Robert Hardman stated in his upcoming biography, "Queen of Our Times: The Life of Queen Elizabeth II," that she suffered private pain when three of her children ended their marriages.

Queen Elizabeth Dealt With Children's Divorces Privately

In an excerpt shared by PEOPLE, Hardman revealed that the Queen found the divorce talks deeply upsetting. One former member of the Royal Household even witnessed Queen Elizabeth II in deep despair.

"I said, 'Ma'am, it seems to be happening everywhere. This is almost common practice.' But she just said, 'Three out of four!' in sheer sadness and exasperation. One shouldn't underestimate the pain she's been through," the unnamed staffer told the royal author.

During the same year - which she has since called "annus horribilis" or horrible year - also saw the incident where a fire destroyed part of Windsor Castle and the damaging issues surrounding Prince Charles and Princess Diana's marriage.

Meanwhile, Queen's former press secretary Charles Anson also told Hardman that he does not remember an event when he saw her exclaimed "No! What's next?" This proved that she was "never short; never irritable; completely steady."

As for where the Queen learned to control herself and things around her, the royal author noted that her stillness was an approach she adopted from her father, the late King George VI.

READ ALSO: Princess Diana's Death Still Makes People Sad, Prince George's Godmother Says

"Her mother's strategy in these situations- to carry on as if they were not happening-had earned her the nickname 'imperial ostrich' among royal staff," Hardman continued. "The Queen's response, as ever, was to follow the example of her father, absorbed from his days at sea, and to treat adversity like the ocean."

Prince Charles and Princess Diana got separated in 1992, years before their divorce was finalized in 1996. Prince Andrew and Sarah Ferguson also called it quits during the same year and waited four years to settle it.

Meanwhile, Princess Anne and Captain Mark Phillips ended their marriage in 1981 and finalized it in 1992.

READ MORE: Norman Reedus Health Status: Is 'Walking Dead' Actor Okay After Head Injury on Set?