Hero's Book or Heroine's Book?

A romance involves two main characters, the hero and the heroine. However, each novel is more the story of one character than the other. You can't tell simply by the opening of the book. It may open in the hero's POV (point of view) yet be the heroine's story.

How does the author decide whose story a book is?

Sometimes the author may not realize the answer until he/she is into the book. For instance, the author may plot the book as if it's equal. During writing, though, one character's story will emerge larger than the other character's. Let's use a movie reference because that's so easy. "Sleepless In Seattle" was Annie's (Meg Ryan's character) story.

How do we know? Who has the most at stake or will lose? The Tom Hanks character isn't moving--he's already lost his wife and relocated. Now all he's losing is sleep. Meg Ryan's character gives up her lifestyle and her fiancé to meet Tom Hanks and will ultimately (we presume) give up her job and relocate to Seattle to be with him.

As you're writing your story, who has the most at stake? Whose life will be forever altered by the outcome. Yes, both will be altered because of the committment. One will totally change, though, even if the ending is a compromise.

Can you think of other instances where the story is clearly that of one main character?