The male character in Taylor Swift’s “august” storyline is named James.
The song presents the viewpoint of a girl involved in a brief summer romance with James. He is already connected to Betty, and the relationship in “august” ultimately ends when James returns to his former lover.
The story continues across three Folklore songs. “august” gives the perspective of the unnamed girl, “cardigan” follows Betty’s perspective, and “betty” is told from James’s perspective. Together, the songs form a fictional love triangle rather than three autobiographical accounts.
A common mistake is treating “August” as the girl’s confirmed personal name. Wikipedia describes her as an unnamed female character, while fans often use “Augustine” as a convenient label based on the narrative. James, however, is explicitly the male character’s name in the story.