In Austen times it was definitely more common for female characters to undergo some sort of a change for the man their loved. Women were the ones that were expected to 'trap' a good man, fit in with his family, and fullfill their obligations as a wife.

Even some of Austen books have that theme.

Was it novel for her to do the opposite? I think it's safe to say that yes, since romantic fiction wasn't a thing before the 18th century. Perhaps there exist some earlier stories that included a similar concept, but I'm not aware of any.