Happening:
He could not believe that this was happening. He wouldn't believe it, because it simply couldn't be happening. It was as simple as that really.
Except:
Except for that fact that it was, and there was nothing he could do about it.
Truthfully:
Truthfully, he didn't actually want to do anything about it, but the part of his brain that had decided that, the bit that didn't lie and knew what he wanted, simply didn't inform the rest of his brain of its decision. It would be terribly counterproductive.
However:
However, as was stated before, he wasn't admitting anything and it wasn't happening anyway so this was all just a random bout of insanity and he shouldn't waste anymore brain power on it.
Especially:
Especially since Aido Hanabusa had the sinking suspicion that he entirely lacked the will power required to make Zero Kiriyu stop kissing him like it was the best and most wonderful thing he'd ever done.
Know:
And just in case you were wondering it was terrible and he wasn't enjoying it in the least.
Polite:
He was just, you know, being polite, by not pushing the hunter away that was all. Nothing more to it really, besides, it wasn't happening anyway.