Oh shit, he's not as dense as I thought he was. I'm glad he was able to connect those things and show he's just not an accepting idiot.
Now that he knows about the things being talked behind her back, maybe he will be more proactive in defending her than just making it up as a game to play.
This manga is so blessed that it can turn a sudden dramatic bombshell into a wholesome moment that doesn't feel like a contrivance.
Quite the feat, considering.