Queen Elizabeth II is, undeniably, the longest-reigning monarch in history. While serving the British monarchy, the first daughter of King George VI was hounded with various issues and controversies, including her alleged love-hate relationship with the late Princess Diana. Her Majesty, despite being divorced from her son, Prince Charles, was not pleased with her late daughter-in-law when it came to breaking royal protocols.

Recent reports revealed that Queen Elizabeth II was unhappy with the mother of Prince William and Prince Harry when she released an official statement about her then-impending divorce from Prince Charles. Princess Diana, according to Anthony Holden's book called "Charles: A Biography," failed to consult the royal family about her plans in releasing a public statement.

"So furious was the Queen about Diana's pre-emption of palace protocol that she gave aides rare authorization to leak her displeasure," Anthony wrote. "The Queen was 'most interested,' mused her spokesman, to hear that the Princess of Wales had agreed to divorce her son. Her opinion was circulated to the press, telling of her irritation over Diana not having contacted her first."

Rumors have it that, initially, Queen Elizabeth II thought Princess Diana was the best woman for Prince Charles after Her Majesty did not allow her first son's relationship with Camilla Parker-Bowles. The queen and Diana were, reportedly, became closer when the latter went to the British ruler for some marriage advice after learning about the affair of Camilla and her husband.

Though they maintained a good relationship for a while, Princess Diana's declining well-being, allegedly, put a strain on their relationship as it, reportedly, became a lot for Queen Elizabeth II to handle. Things got even worse when the mom of two had collaborated with a writer for a royal family-tell-all book.

Royal biographer Andrew Morton even claimed, in 1997, the book that centered on Princess Diana's life while she was still part of the Royal family directly came from her.  Before Andrew's claims, many had suspected that the Princess of Wales had leaked private information about the Royal family to her friends in media. Good Housekeeping even claimed that, from her style choices and humanitarian works, Diana proved that "she was a regal rebel." Despite their alleged love-hate relationship with each other, Queen Elizabeth has remained a loving grandmother to Diana and Prince Charles' two sons, Prince William, and Prince Harry.