Oh yes, that is definitely a trope, but I'd never seen it done this way before. Over 5 seasons, where the male character changes so completely and the women constantly pushes him away. If Buffy had fallen for him from day one and he'd changed from day two, that's expected. But Buffy pushed him away constantly and he changed constantly. Maybe that happens a lot and I've just not watched enough tv, but from what I see, a gorgeous vampire shows up, bats his eyelashes and the good girl falls for him straight away, and suddenly he's not so bad. For me, that's not the Spuffy story at all.I think the opposite. The heroin falling in love with his enemy is something very common in television history.