AnimeQuest

Hi! I'm new to this but I'm hoping you all can help me! I'm looking for an anime I watched a long time ago, and I can't remember what it's called. The main details I remember are that it's a magical girl one, I believe set in a high school, and one of the antagonists is this dark haired, sort of nerd type guy who loves the MC but hates her alter ego. In the episode I remember, he actually finds out that they're the same person, and it freaks him out, like sends him in a spiral of chaos (possibly because he works for the Big Bad? unclear). Anyway, that's basically all I remember! I've tried searching but it unsurprisingly didn't work because I have so little info. The only other clue I have is that I know I saw it from one of the DVDs Otaku magazine would come with (so this would have been like, 2008). Thank you!