OK! Reveals the Single Thing That 'Drove' Charles 'Mad' During His Marriage to 'Difficult Diana'

OK! can reveal King Charles' conduct is being re-examined through the lens of his first marriage, with fresh claims one deeply personal dynamic inside his torturous relationship with Princess Diana proved impossible for him to manage and helped accelerate the collapse of their union.

Charles, now 77, married Diana Spencer on July 29, 1981, in a globally televised ceremony at St Paul's Cathedral, London, that was widely framed as a modern royal fairytale.

Behind the scenes, however, the former Prince of Wales struggled with aspects of his young wife's temperament, according to sources who spent years as Diana's closest confidantes during her most difficult years.

One of the tragic royal's friends said Diana was "emotionally unpredictable" – a quality they said unsettled Charles more than anything else.

They said: "Diana could shift emotionally very quickly – she had a hair-trigger personality. "

At times, she was warm, animated and engaging, but if something unsettled her, the temperature in the room would drop almost instantly.

"That volatility, combined with her youth, was something Charles found deeply challenging and often struggled to understand. In less polite terms, it drove him mad and led him to call her 'Difficult Diana.'"

The age gap was another significant factor in the pair's fractured marriage.

Charles was 32 at the time of the wedding, while Diana had turned 20 just weeks before their nuptials.

Royal insiders say the difference in life experience only widened the emotional disconnect, particularly under the relentless pressure of public scrutiny.

One former palace aide said: "Charles approached life in a measured, private way, preferring structure and routine, while Diana lived very much through her emotions. That fundamental mismatch surfaced day after day, and over time it drained him emotionally."

Charles and Diana's marriage also unfolded under extraordinary circumstances. The future king entered the union while still emotionally attached to Camilla Parker Bowles, now Queen Camilla, 78, who attended his wedding to Di.

Diana, meanwhile, was thrust overnight from teenage anonymity into the most scrutinized role in Britain. Friends later said she was unprepared for the isolation and formality of royal life.

When they married, Diana told her biographer Andrew Morton: "I remember being so in love with my husband that I couldn't take my eyes off him. I just absolutely thought I was the luckiest girl in the world. He was going to look after me."

The statement would later be read as a measure of how starkly reality diverged from expectation.

The couple separated in 1992 after 11 years of marriage and finalized their divorce on August 28, 1996.

Diana died just over a year later in a Paris car crash at age 36. In the years following her split from Charles, both parties acknowledged the relationship had been fundamentally flawed from the outset.

One royal expert said Diana eventually accepted she was not Charles' great love.

They added: "Over time, Diana came to understand that Charles' emotional allegiance lay elsewhere. She recognized that Camilla occupied a place in his life that she never truly could."

The insider also said: "Diana once reflected that she wished she had shared their early love letters, because they showed that Charles did care for her at the start. But she also accepted that the marriage was never built on choice or compatibility – it was a match arranged by circumstance rather than love."

Those close to Charles say the experience permanently shaped his approach to relationships and duty.

One former adviser said: "The intensity and instability of that relationship had a lasting impact on Charles. It taught him, painfully, the consequences of allowing duty and expectation to override genuine emotional compatibility."