Original sentence: Lightfoot has acknowledged that his musical touring and the difficulty of fidelity in a long-distance relationship contributed to the failure of at least two relationships:.They divorced in 1973, the marriage ending in part because of his infidelity
Edited sentence: Lightfoot has acknowledged that his musical touring, and the difficulty of fidelity in a long-distance relationship, contributed to the failure of at least two relationships:.They divorced in 1973, the marriage ending in part because of his infidelity (with his then girlfriend, Cathy Smith, a rock groupie who went on to serve 15 months in the California state prison system for injecting John Belushi with a fatal dose of heroin and cocaine in 1982 )