I had a friend ask me this question some time ago and we tried to talk through it but ended up still stumped. The story went: if there is a husband and wife in a happy marriage but the husband goes away on a business trip, maybe has a little too much to drink or just has a lapse in judgement, and has a one-night stand with another woman and knows it was a morally wrong act does he have the obligation to tell her even though it will devastate her and potentially end her marriage? Or should the husband keep quiet and live quietly with the shame he has brought on his marriage? If an immoral act has already been committed does it do any good to be truthful about it and bring further harm to others, as would happen if the wife were told? It just seems that if it is immoral to do harm to others than telling the wife might just be as immoral as the act of adultery.