Princess Anne and Timothy Laurence have been enjoying 28 years of marriage. But before this happened, the couple faced a controversial issue when the Princess of York's love letters were stolen and publicized. As their secret affair got exposed, here's why Queen Elizabeth II's only daughter and the retired Royal Navy officer's love was dubbed to be a "dangerous liaison."

It was in 1989 that the 69-year-old royal's secret affair with Her Majesty's equerry was exposed. At the time, she was still married to her first husband, Captain Mark Phillips.

According to Daily Express, Princess Anne was constantly visiting Timothy Laurence at his Winchester home and no one knew about it. In a 2002 Channel 4 documentary, The Real Princess Anne, former royal reporter Ashley Walton revealed that even the media didn't know about their affair.

"The neighbors knew, that's the extraordinary thing - most of the people who lived in the road knew that Anne was coming there regularly for weekends," he said. Although they noticed that Princess Anne often visited, nobody told anyone about it. As a famous figure, it was an extraordinary thing.

Walton went on to say that Princess Anne has loyalty, and everybody likes her. She also has a lovely personality and says hello to everyone. Hence, she gets people's loyalty in return, although they don't know her or have nothing to with her. Nobody dared to tell anyone, even the media for that matter, about her secret affair.

But, when her love letters were stolen inside the Buckingham Palace and sent to The Sun, an investigation began. Sadly, despite the rigorous investigation that went for months, the thief remained unknown.

Buckingham Palace then admitted that the stolen letters were from the then-commander Timothy Laurence, Queen Elizabeth's equerry, addressed to Princess Anne. Although it didn't reveal its content, the affair was branded a "dangerous liaison" by People magazine and the Channel 4 documentary  The Real Princess Anne.

Although Princess Anne and Mark Phillips' marriage at the time was already strained by rumors of infidelity on her husband's side, this exposé ramped-up their separation. Eventually, they got divorced in April 1992.

Months later, Harper's Bazaar noted that Princess Anne and Timothy Laurence got married in the same year. They tied the knot in Scotland, in a small church close to Balmoral because the Church of England didn't allow remarriage at the time. Now, they will be celebrating 28 years of marriage, and their love seems to be going strong.