"I noticed that," Terrence said dryly. It had been somewhat comforting to realize that he wasn't the only one afflicted, though it also disturbed him. "I'm not used to falling for the same tricks everyone else does. Especially since she doesn't seem worth it. Etiquette? Come on. I'd never bother taking that class if it weren't for, well."
He just didn't get it. There had always been pretty girls, and sure, he was a warm-blooded male, it wasn't like he hadn't admired a few just for aesthetic reasons. But he didn't like them unless they were worth liking, and he certainly didn't change his behavior for them.
If it had been Tracey Davis teaching the class, sure. It would be amusing to see her teach etiquette, after the last conversation he'd had with her. And there was always Ella Lestrange, who captained his Quidditch team, and he had no complaints about following her lead - she was a wicked genius. But he saw nothing else in Fleur Delacour.