In romance jargon, "hero" is the male lead and "heroine" is the female lead. The aim of the story is to get the two of them together in a happily-ever-after.
But, in the classroom, Fio always taught her students that "hero/heroine" referred to a value system and indicated a virtuous, super-good person (think Mighty Mouse). The main character of a story, she taught, should properly be referred to as the "protagonist," while whoever or whatever opposed the protagonist was the "antagonist."
Thus, in romances, the lead female is the protagonist while the lead male is the antagonist. How odd that even though the story is about a relationship, not about values, value-heavy terms are used.
But, what the heck. Fio's finally jumped on the band wagon. Please excuse her now. She has to rewrite chapter two to deepen her hero's point of view.