No, it's not acceptable, but she called him and told him. She's looking for a reaction, not an affair, I think. Give her the reaction, and she uses it to justify whatever she does next. Leave it be, and she gets a dinner out of it, and no reaction. Looking the other way, what's the alternative? Tell her she can't go? Like that would work! Then where are you? Where do you go from there? I don't know, but I think his way of handling it made sense, for this case, at this time.
