I agree that she should return the ring, even though I'd always heard that if he breaks the engagement, she gets to keep it. (I think I read that in Emily Post about 40 years ago.) However, I think he should reimburse her, though I wouldn't hold my breath until he does. I've never understood why anybody would want to keep an engagement ring they're not going to wear. The line "diamonds are a good investment" was made up by diamond companies, because you can only hock it for a fraction of its worth, or trade up, which means spending even more money. And don't even get me started on the "two month's salary" nonsense. That's definitely a diamond company creation.

Joannakathryn and Miffed,

The ring is a part of a contract to be married. The contract was broken; the ring is to be returned. This is not about etiquette but legality. Regardless of who broke the contract the marriage did not take place. He does not have to nor should he reimburse her.

I really liked the article

Observation: in all the decades I've been reading letters to advice columnists, never once has the phrase "My friends all say ..." been linked to sensible advice from friends. Someone should study why female (mostly) and male friends all offer bum advice which, if followed, will widen a split or doom a relationship. Mean spirited? Jealous? Consistently stupid?
Someone should fund a study ...