Dolly Parton originally wrote and recorded I Will Always Love You in 1973, as a farewell for her former mentor and collaborator Porter Wagoner. That was soon after she decided to pursue a solo career. She reworked her cult classic in 1974 for The Best Little Whorehouse in Texas that was released in 1982.
The affair went on despite their professions having them on opposite sides of the law. After a long flimsy battle, the authorities shut down the Chicken Ranch; Miss Mona and her girls had to move away.
In the scene where he sings Reynolds, I Will Always Love You, Mona is about to leave town, and Ed arrives just in time to stop her. He finds her bags packed at the back of a truck and hurriedly walks into the house to profess his love for her and propose marriage.