His bubble of ignorance was popped on a Friday night. The Slytherins had their own rooms so privacy had never been an issue for him, a simple twist of his wand was enough to lock the door if he wanted some alone time, so that's what he did. He was done with homework at the moment, Potter had made a fool of himself in Snape's class, and he had an idea for a new potion he wanted to create, so in theory it should have been a good night to satisfy his physical needs.