They started touring together
By the early 1960s, Carter was touring with Cash regularly as a backup singer, duet partner, and entertainer. She had by that time divorced from Carl Smith, but was now married to a police officer named Edwin Nix, with whom she would have another daughter, Rosie, who also became a country musician.
Both Carter and Cash would remain married to their spouses until 1966 and 1967 respectively (Vivian filed for divorce in 1966 but it was not granted until later the following year.)
Despite the fact that their romance become something of a country music fairytale, the couple was relatively circumspect throughout the years regarding the beginning of their relationship.
“I never talked much about how I fell in love with John,” Carter Cash told Rolling Stone in 2000. “It was not a convenient time for me to fall in love with him, and it wasn’t a convenient time for him to fall in love with me. … I was frightened of his way of life. I thought, I can’t fall in love with this man, but it’s just like a ring of fire.”
It was this thought that inspired her to co-write Cash’s hit song “Ring of Fire” with Merle Kilgore. (The song was originally released as a single by Carter’s sister Anita before being recorded by Cash in 1963.)