Definitely, Maybe

Drarry fluff based on the prompt that Person A had their headphones in when Person B first asked them out, so A didn't really hear B and was just nodding along to the music, and now they've been going out for months. And when someone mentions it, A is like "Wha? I didn't know we were dating." Muggle AU, university setting. Snobby sweet Draco and oblivious Harry.