Utena is going to wake up in the middle of the night with a sudden realization:

There is no way that, when Corwin and Anthy get married, she'll be able to get out of officiating the ceremony.

She's gotten married twice, but she's never performed a marriage herself, what will she do?

And then Corwin or Anthy will remind her that she'll do what she always does in that kind of situation: her best.