A subtler theme in Utena is the unreliability of human memory, even (especially?) when it comes to the most important moments. The day Utena met the prince was probably the most important day in her life - it utterly shaped her future, from where she attended school to who she associated with (remember: if she hadn’t gotten the ring, she would’ve never been challenged to a duel).
Utena cannot actually remember what happened that day with any degree of accuracy. This becomes increasingly obvious throughout the series, though it’s still pretty clear in the beginning, when she’s not quite sure whether Touga is her prince or not (and see how similar they are in appearance…). Utena cannot recall that she’s previously met Anthy before even though meeting Anthy was the event that made her want to be a prince in the first place.
I’ve spoken about this before (here), but Mikage’s arc also foreshadows this theme. Mikage’s memory is also very bad concerning those days that were so important to him, back when he spent time with Tokiko and Mamiya. He, too, cannot remember what the most important people in his past looked like, and this allows him to be deceived and led around by the nose by End of the World. Mamiya even makes the comparison to Utena himself - we both met important people in the past, didn’t we? - but she doesn’t get it, and probably the viewer won’t get it, until much later in the series. Mamiya’s fatal flaw is also one shared by Utena, and by a huge number of human beings in general. Human memory is powerfully, vastly unreliable. If we repeat a lie too often, to us it can become the truth.