The writer Craig Brown once noted of the Duke and Duchess of Windsor that “books have been written proving conclusively that they were a good thing and that they were a bad thing; that she loved him but he didn’t love her; that he loved her but she didn’t love him; that they loved one another and that they both hated one another.”

The books—both fiction and nonfiction, in addition to documentaries, musicals, and films—continue to appear 36 years after her death and 50 years after his and continue to adopt very different points of view toward the couple. Some still argue that this was one of the great love affairs of the 20th century, others that Wallis Simpson, who had been the future King Edward VIII’s mistress since 1934, felt trapped in a marriage that she had never wanted.

“The Duchess rather baffled me,” remembered her wartime P.R. spokesman, Rene MacColl. “What causes one human being to fall madly in love with another is occasionally clear to third persons. More often it remains a mystery to the onlooker. So far as I was concerned, it was emphatically a mystery in this case.”

Some argue that this was one of the great love affairs of the 20th century, others that Wallis Simpson felt trapped in a marriage that she had never wanted.

What was not in doubt was Edward’s obsession with Simpson. In 1936 he threatened to commit suicide if she did not marry him, and to his death in 1972 he remained devoted. His friend Lord Birkenhead believed that “to him she was the perfect woman,” while Winston Churchill, one of the Duke’s greatest supporters during the abdication crisis in December 1936, thought he “found in her qualities as necessary to his happiness as the air he breathed.”

The evidence of Simpson’s affection for Edward is less apparent. She seems to have enjoyed the status and social contact that her relationship with him brought, but it is doubtful she was ever in love with him or fully considered the implications of the relationship.

As far back as their Mediterranean cruise on the Nahlin in August 1936, when the affair first became public knowledge, Lady Diana Cooper, a socialite who was on the yacht as a guest of the King, had noticed that Simpson did not want to be left alone with him. She wrote in her diary: “The truth is she’s bored stiff with him, and her picking on him and her coldness towards him far from policy are irritation and boredom.”

The duchess and duke pick flowers on the grounds of their home, le Moulin de la Tuilerie, outside Paris, 1955.

“The duchess was a complicated person—cold, mean-spirited, a bully and a sadist,” observed Gaea Leinhardt, the stepdaughter of Simpson’s ghostwriter, Cleveland Amory. “My parents found the duke not very bright, a wimp, and basically a very sad man. He had made an appalling choice and knew that he had taken the wrong path and now had to live with the consequences. They found him pathetic.”

Yet in some ways, it was precisely Simpson’s dominant manner that most appealed to the duke. Mona Eldridge, who met the Windsors on numerous occasions while working for the Woolworth heiress Barbara Hutton, later wrote, “People on her staff told me how she would reprimand the Duke like a harsh mother with a naughty child, not infrequently reducing him to tears. Paradoxically, this only caused him to cling more tightly to her.”

Kenneth de Courcy, the British editor and confidant to Edward, would later write:

Did she love the Duke of Windsor? I am afraid the sad answer is that she did not. She admires him, she likes him, but it never went further and I think he knew it and it was that which made him restless and induced him to concede his very innermost person to her authority in the hope that love would come.

So much for the legend of the great love affair.

Andrew Lownie is the author of several books, including Stalin’s Englishman and The Mountbattens. His latest, Traitor King: The Scandalous Exile of the Duke & Duchess of Windsor, is out now from Pegasus