I think dismissing the relationship between Utena and Kiwi simply because there's been no high drama between them since their first battle is a fundamentally unhealthy view of the characters. Utena is shown to honestly love basically every girl we've seen so far in some way. Her primary challenge in the Enorme arc was finding something to love about a person she straight-up dislikes.
At this point, her interactions with Kiwi can be described as "cozy domesticity", which is indeed something that someone who's dom can still value. I don't recall her ever showing annoyance or dismissal in response to Kiwi's sappy proclamations. Mostly it seems to be a trait that she understands and rolls with.
Whether Utena x Sayo is certain is something I'm not confident on at this point, but I'll say she basically demonstrates similar interest in "bringing out the best of" each member of Tres Magia. I think what others are saying about Utena not feeling deserving of their affection/love is the real conflict that would have to be overcome for a lasting relationship to form.
Kiwi x Kaoruko is a bad idea and I hope these beach chapters aren't a setup for it without significant development between them. Partners constantly tearing each other down isn't cute; it's mean and nasty.