Elvis Presley had an affair with 'Viva Las Vegas' co-star Ann Margret behind Priscilla's back

Elvis Presley's personal life was far from perfect despite the glitz and glamor of his career. For all the songs his relationship inspired, the King of Rock n' Roll's marriage to Priscilla Presley wasn't as perfect as one might imagine.

Elvis first met Priscilla in 1958 while he was stationed in Friedberg, Germany. He had been drafted into the US Army and wasted no time before striking up a relationship with the 14-year-old woman, whose last name was Beaulieu at the time. The star left the army two years later and returned to the US, but Priscilla realized that she couldn't get away from her lover, so she started visiting him from time to time. She eventually moved to Graceland, Memphis in 1963, permanently. However, she would soon witness another side of the actor and performer that she hadn't seen before.

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Elvis was working day and night to make it in Hollywood at the time, pursuing his childhood dream of becoming a serious actor. His boss, Colonel Tom Parker, made some deals to get him in front of a camera. He had already made 13 movies by 1963, playing the musical love interest in most of them. Later, he admitted that he was frustrated by the simplistic content of the movies, but he nevertheless worked hard on every film set.

Singer Elvis Presley holds actress Jennifer Holden, his co-star in the movie 'Jailhouse Rock,' as they spend time together in a swimming pool, circa 1957.

Priscilla understood Elvis's passion for work and decided not to visit him in Los Angeles on the sets of her movies so he could focus. Instead of her, she stayed at Graceland. The young Ella spoke about her relationship with the world-famous artist in the August 1973 issue of Ladies Home Journals. "I didn't think he could go all out if I was around," Priscilla wrote at the time. "I felt like that was his job, his business, and it wasn't my place to be there. Most of the time I stayed in Memphis and filled my time in the dance studio, or went out to dinner with a friend. He was perfectly happy the way he was."