Well, that sure seems like the sort of thought that could get in the way of a happy relationship. That makes Keltham's correct course of action here very clear.
He's going to announce now that he's taking tomorrow off announce that tomorrow, it may inconvenience others but he doesn’t want his brain thinking that the Conspiracy successfully deduced what that request meant in context and stayed up all night to prepare. He’s taken days off before, but maybe he’d ask for this one with a facial microexpression that gave it away, or somebody would make an inference from the precise timing of the request. If he’s doing this at all, he’ll do it with a pretense of security mindset, so his brain doesn’t think he could try again better.
He’ll spend some time tonight figuring out what to try, and which spells to request tomorrow at dawn.