Goin' South (1978)

Henry Moon is captured for a capital offense by a posse when his horse quits while trying to escape to Mexico. He finds that there is a post-Civil War law in the small town that any single or widowed woman can save him from the gallows by marrying him. Julia Tate needs a man to help her work her mine and marries him. The sheriff makes it very clear to Moon what the consequences of his leaving Julia will be. The two begin to try to form a relationship based on necessity in which they have nothing in common.