Really, Draco was the only one Astoria would trust to say anything about Daphne around. Granted, her relationship with him was somewhat of the cause of Daphne's hate, but Astoria didn't care. She wasn't breaking her relationship off due to her sister's jealousy. Either Daphne could be happy with Dean or she couldn't - that had nothing to do with Astoria and Draco. "Have I mentioned lately how brilliant you are?"
"And oh, you're bed." Astoria was already somewhat tempted to doze off on Draco, then and there. Still, the laugh was enough to prompt her to smile and keep the conversation up. "But surely your mother wouldn't approve of that part. What if the house elf told her I wasn't staying in 'my' room or if she knocked in the morning for some reason or other and discovered my empty bed?"