Has anybody actually told his fiancée - who has (or soon will have) a meaningful ring of her own to treasure - that he has done this? Has he said anything about it to her or is he ashamed to? (Or pretending he has - you can't trust a thief not to also lie about this.) Or: does she approve?

It would be interesting to see his reaction if you "threaten" (even jokingly) to tell her.