How could a person "sort of’ have sex? Well, Draco thought he had one that might count, but it was entirely different. It had been after a blazing row with Daphne over something or other, and Draco had thought they were past it, moving onto makeup sex. She’d let him get two seconds worth of entry before telling him to get the hell off her, that she was still mad. So that was probably a "sort of,’ but not the same vein as what Granger had inferred.