His face loses the edge of anger as it's slowly replaced with anxiety. Arche is simply too insistent to be lying on purpose. Maybe she's insane? Or maybe...

The alternative, the idea that she could be right, makes his face actively grow pale.

"No, no, that cannot be so..." He says, his voice trailing off. It sounds like he's genuinely trying to convince himself now, rather than the confidence he had before, "I think I need to have a lie down." The genuine distress is kicking in, boy does he wish he had a glass of wine right about now.