In Ms. Calendar's defense, I have to say that I never fully understood the intense hatred she provoked in Giles and Buffy (moreso the latter). Yes, she knew about the curse. Yes, she lied about who she was. But, as she stated more than once, she had no idea that Angel would become Angelus after experiencing true happiness. And, after all, Angelus had tortured her people. Although Giles was clearly ready to forgive her in this episode, Buffy continued to use her as a scapegoat for what happened to Angel. I guess you can hardly blame a 17 year old girl, though, of course, the slayer is ideally much more mature than that.