It's an obvious lie of exclusion - he probably isn't kidding about loving his happy endings, but that certainly isn't why this matters so much to him. Arthur's sudden intensity draws his eyes back up, and for a moment he looks once again like he did when Dumage yanked the door open on them - as if this might very well be the single worst moment of his entire existence. He stares back at the other silently for a long moment trying to compose himself beyond what seems like a terror that grips him to the very core.

What seems clear is that it's not even a fear of Arthur, but of what this moment might mean.

Finally, he says, in a tight voice that seems to beg the other to just let it lie: "It isn't something I can talk about."