Draco had been amused, but that amusement faded at the lie. He knew he'd startled her, he'd have even apologized, except that he didn't need to be a trained in occlumency and legilimency to know that she'd lied to him - it was obvious in every bit of her, clear in her eyes.
"Astoria - " he said, carefully, though there was something sharp under it that was never there when he spoke to her, only when he spoke to others. He never expected her to lie to him, though, when he always expected it from others.