I mean, I would think there would still be an aspect of secrecy and shame for the female cadets which would make it not talked about, and it would not be something going on out in the open for the male officers where he might have observed it. And then the fact that he and Elizabeth had been married and known each other for nearly 20 years at that point, I think we can read from his reaction in the bedroom of, "So why didn't you tell me about Timoshev?" that they had gotten to a level of comfort around each other that he kind of expected she would've said something if that'd been the case. Of course, we find out over the course of the season that Elizabeth has been keeping a lot of secrets and telling some lies, but at the point Philip is now, he doesn't really know the degree to which she hides herself from everyone.