It is 1917 in the town of Wharton, Texas. On Valentine's Day young Elizabeth Vaughn defies her wealthy parents by running off and marrying a young man of humble prospects.
Her parents have not spoken to her since her marriage, even though the couple lives in a rooming house nearby, they are struggling financially and she is pregnant.
This film, to some extent autobiographical, is based on the story of writer Horton Foote's mother and father. 'On Valentine's Day' is about the unselfish love of a man and a woman, about abiding love within a family, about the emptiness of living without love - all enduring themes of human existence.