Please assume *anything* you tell me will be told to my wife. I don't literally find time to mention every detail of everything I do -- there aren't enough hours in the day, and a lot of it she doesn't care about.
But she's welcome to every detail she wants, and empowered technically to find out whatever she likes, within the realm of what I know.
Please just don't send me anything you wouldn't want her to know. Full stop.
(Okay, so, like birthday planning and things like that? Sure, within normal limits and for limited duration. But assume that before long, those messages too will be readable by her.)
A "don't tell Krissy" disclaimer is, naturally, worse than no disclaimer at all, because it marks that as something of interest to her. And I don't hide stuff from her, whether by actively doing so or by strategic not-mentioning.