While Cor clearly has had a better day that Noctis did, he's not entirely insensitive to how the younger man must be feeling right now. The fact that Noct's not trying to push him away in belated disgust - or worse, weep in shame over what just happened - is a small blessing in of itself, in Cor's mind.

He lifts his head in confusion for a moment, noticing Noct's belated embarrassment. But everything gets cleared up when some of his fellow warriors start singing a wedding drinking song...about the two of them. "...remind me to beat them after I get dressed," he sighs into the prince's shoulder. Not because Cor's embarrassed himself, but because he's cringing at how off-key those assholes are being.