One thing which has always puzzled me about JA's society is why it was considered so horrible for a man to break an engagement, even an unspoken one, while a woman could do it at will. Anne Elliot dumps Capt. Wentworth pretty hard, but that's her decision to make -- but when he realizes he's been raising expectations in Louisa, it's his duty as an honourable man to go through with it.

There's also Henry Tilney, defying his father for Catherine even though he'd never actually proposed to her, and Edward Ferrars, ready to live in poverty for a woman he doesn't even like. The only one who leaves the girl is Willoughby and we all know what he was like...

So what would have been wrong with saying "I fear I could not give you the happiness you deserve and may I please have the ring back?"