I recently borrowed my friend’s very expensive silk dress and got a big salad dressing stain right down the front. (Doof.) I had it dry-cleaned and now you honestly can’t see the spot at all, but am I obligated to tell her about the incident?
Yes, you have to tell her about Caesar-Gate 2014, but it doesn’t have to be a big thing. You can simply say, “Thank you so much for lending me the gorgeous ball gown. I had an unfortunate buffet-line spill, but I got the dress cleaned and I think it looks as good as new. Let me know if you disagree and I will of course replace it all together.” Chances are, she’ll feel the way you do and will appreciate your honesty.