Because he knew what Gellert was doing-- and even if he didn't, he knew Gellert was doing something. No one had ever been able to tug at him, been able to make him feel so predictable or so easily maneuvered, as Gellert. And part of Albus hated himself for letting Gellert do it, while its opponent couldn't figure out how to not.
Albus's shirt leaped into his hand with barely a conscious though. Slipping his arms through the sleeves, he covered every inch of his arms and torso that Gellert had touched, the phantom grasp and stroke of his hands burned into Albus's mind with an obnoxious sort of clarity. Although he refused to ashamedly fumble in a haste to stand and don his trousers and cover himself properly once again, he hardly abstained from employing a few simple threads of magic to fasten up every single one of his buttons.
His eyes slipped shut as he tried to wind himself back together, to disengage from the world around him and retreat back into himself. Normally, this was an easy process. Normally, he didn't even have to think about it. This time, however, in this place, his attention kept snagging on his skin. He'd never really thought to spite his skin before, but he was getting close. Albus wouldn't even feel guilty about it; his skin had started it, given the way it kept turning traitorous on him.
"I trust that henceforth you won't require my presence for fittings," Albus said, not looking at Gellert. The words were sluggish, but perfectly carved, as if disuse had made the custom of speaking a bit foreign. He didn't want to discuss things. He didn't want to have a conversation of Gellert leading his points in circles while his head was still spinning. And he wanted to leave, and erase the possibility of this vignette repeating itself before his mutinous hands grabbed at Gellert again.
And how they wanted to-- which was patently ridiculous. Or so he had hoped, at least, that this would be the same as before, that experience would be cathartic, purging even. But he could feel it, his grand miscalculation. It was better. With the sound of Gellert's breath wrapped around his name still ringing in his hears, it was so much worse.