Seeing thing from Anastasius perspective a bit more really helps his character. The point he drives home about how his actions as a member of Royalty always have implications whether he cares for it or not are a bit more understandable.
The disconnect though is still very present in how he treats others he doesn't have any strong interest in like with how he casually mentions Rosemyne fainting like he's a bystander to the ordeal rather than as someone directly involved. Even Eglantine was able to pick up on it to an extent, and had to get him to write an apology to Rosemyne.
Don't be so hard on the kid. He was just overexcited seeing his crush express so much for the first time.
Her blush when he openly expresses his love, her bewilderment when he lists Rozemyne's rude advice
Heck, even her strict face when she scolds is a real treat for him.
He's sharp enough to realize she tenses up when he first mentions Rezemyne.
So he must also realize all those new faces are her real emotions, showing him for the first time.