That one I never understood, because it's not like they couldn't have made it make sense. I mean, obviously, you can't do a "Willow restores Angel's soul and has an epic magic battle with Evil Cordy" episode without Willow being confident about her magic, so there's an inherent conflict there.

But how hard would it have been to write Angel as pretty depressed, and when Buffy asks what's wrong, he just says he doesn't want to talk about it? He can still get jealous of Spike, but be less flirty about it, you know? NOT THAT HARD.