In Taylor Swift's “august” story, Betty's former romantic partner is James.
James is the teenage boy at the center of Folklore’s connected love-triangle songs. In “august,” the unnamed narrator spends a brief summer with him, but James ultimately returns to Betty, his former lover. The same character is addressed more directly in the song “Betty,” which presents his side of the story.
The three-track structure gives James a different role in each song. “Cardigan” looks back from Betty’s perspective, “august” focuses on the girl who believed the summer romance might become more, and “Betty” shows James attempting to explain his actions.
The narrator of “august” is not officially named in the lyrics. Swift said she privately thought of that character as Augusta or Augustine, but those names are not the answer to the question about Betty’s romantic partner. James is the clearly named male character in the triangle.