Ok, I hit the TV Tropes site entry on this series, and it’s a lock, I’m not bothering any more with it…
Mind Screw (Everything in the series can qualify if you think about it.)
Not Blood Siblings (Inversion; Nanami loves her brother (If You Know What I Mean), but is crushed after finding out they are both adopted and not blood related after all. This is then subverted when it turns out that Touga was just playing with her head â€” while they are adopted, they were adopted from the same family and thus actually are blood siblings. For the record: This is the Double Subversion of the Inversion of a trope â€” a prime example of how Mind Screwy this show is.)
But the one that really did it was:
Love Dodecahedron (*Deep breath*: Utena idolizes Dios and loves Anthy but gets tempted by Touga and Akio, the latter who is engaged to Kanae. Anthy mourns Dios, has love/hate feelings towards Utena and Akio, and is pursued by Saionji and Miki. Saionji, who may-or-may-not return Wakaba’s feelings, may-or-may-not love Touga, who may-or-may-not love him back, but seduces hordes of schoolgirls anyways and attracts both Keiko and Nanami. Tsuwabuki loves Nanami just as creepily as Kozue loves Miki and willingly sleeps with Akio. And Mikage once loved Tsukiko, who was seduced by Akio, and now loves Mamiya, who is Anthy in disguise. Meanwhile, Juri, Shiori, and Ruka have their own love triangle all to themselves, but Juri may-or-may-not love Miki in the movie, and Akio manipulates the emotions of all of the above to keep them in the Duels.)
I should have realized it when one troper mentioned that this series had a Gainax ending… and a Gainax beginning to go with the Gainax middle.
I’m outta here…