Buffy the Vampire Slayer - Season 4 Episode 19 -

Tara and Willow's relationship seems to be progressing when Oz returns to town. Through his travels Oz has found a combination of charms, potions and meditation that allows him to avoid turning into a werewolf. When Oz discovers that Willow and Tara are more than friends he loses control and as a werewolf chases Tara.