Johnny Cash and June Carter Cash were one of country music’s most legendary couples, and the Man in Black’s proposal to his future wife was something straight out of a movie — literally.

Cash and June Carter, with whom he had toured and performed extensively, had already weathered a number of personal storms together when Cash surprised her with an onstage proposal during a gig in London, Ontario, Canada, on Feb. 22, 1968. The moment was later depicted as one of the pivotal scenes in the Oscar-winning Cash biopic I Walk the Line, which starred Joaquin Phoenix as Cash and Reese Witherspoon as Carter.

Cash and Carter met for the first time backstage at the Grand Ole Opry in 1956, at a time when Carter was singing with Elvis Presley. Cash was married to his first wife, Vivian Liberto, at the time, but after 12 years and four daughters together, Liberto filed for divorce from Cash, citing his ongoing addictions and alleging extramarital affairs.

Liberto, who died in 2005, called the divorce a “degrading, horrible experience” in her autobiography, I Walk the Line: My Life With Johnny, and contrary to the rosy picture that’s generally portrayed of Carter, she blamed her for the split, saying June set out to steal her husband deliberately.

“I should have been relentless at saving” the marriage, Liberto wrote, “as relentless as June was at destroying it.”

They finalized their divorce by the end of 1967, and Cash wed Carter on March 1, 1968, less than two weeks after his public proposal. They had one child together, John Carter Cash, who was born in 1970. The couple continued to perform together and released several collaborative albums, including Carryin’ on With Johnny Cash and June Carter, Johnny & June and June Carter and Johnny Cash: Duets.

Their son would later reveal that all was not always rosy in his parents’ marriage in his own book, Anchored in Love: An Intimate Portrait of June Carter Cash, which detailed his father’s continued infidelities in his second marriage, as well as both of his parents’ addictions. But through all their ups and downs, the couple remained a source of inspiration for their steadfast love.

“The love that John and I share with our love for Christ is one of the most precious gifts God could have given us,” June Carter said of Cash.

Cash wrote a love letter to June in 1994, on her 65th birthday, that was named the greatest love letter of all time in 2015.

“Sometimes we irritate each other a little bit. Maybe sometimes take each other for granted,” Cash wrote. “But once in awhile, like today, I meditate on it and realize how lucky I am to share my life with the greatest woman I ever met. You still fascinate and inspire me. You influence me for the better. You’re the object of my desire, the #1 Earthly reason for my existence. I love you very much.”

In fact, it turned out that Cash couldn’t live without his wife. Carter died on May 15, 2003, and Cash followed less than four months later, on Sept. 12, 2003.