Despite Diana's love affairs during her final years, her husband remained her one true love, Lucia Flecha de Lima has stated.
The former ambassador's wife rarely speaks of her friendship with the Princess. She made her rare comments at the Brazil premiere of Diana, which focuses on the royal's relationship with heart surgeon Hasnat Khan.
"If you ask me if she had some passion for Hasnat, I don't know, it is possible," Lucia said.
"But for Dodi Fayed I am certain she did not. I know because I asked her."
She added, "The love of Diana's life was Prince Charles, I have no doubt about this."
Lucia, the wife of a former Brazilian ambassador to London, became friends with the Princess in 1990, meeting her at an official function after her husband was appointed to the Court of St James.
The two ladies became so close they would meet several times a week, and when Lucia's husband was posted to Washington in 1993, they spoke on the phone daily.
She even spoke to the Princess during her final holiday with Dodi Al Fayed.
Lucia — who once told her friend she thought of her as Latin rather than English, because she was so passionate — said Diana believed Charles was in love with her when they married, and recalled him being "enchanted" when their son Prince William was born.
She also noted that Charles and Diana did not have the opportunities now available to the modern royals.
"Look at the relationship between Prince William and Kate," she said in comparison. "They chose to spend the first two months of their son's life with her family. This was simply unthinkable years ago."