I know this has happened to others, but am livid!
My wife-sim was at home painting all alone all afternoon but when her husband came home he accused her of cheating on him! He's got the betrayed moodlet for 5 days at -50 mood! It reset their relationship bar to nil. I couldn't get them to sleep in the same bed for 2 nights. When it happened, I clicked on the item in the cue to stop it but it just kept popping back up.
I've been able to get them back on the right path, and have written it into the story line, (am trying to found an Immortal Dynasty.) but o, dear, the language I'd like to use would have Pam kick me off the forum forever!
I'm so glad I'd heard that this can happen before it did happen to me, otherwise I think I would have cried.