Don't think I've ever resent a character as much as I do for Kaoru, she's literally the last person on earth I want to see my Uta with, given this is a fiction I'd love to see her with Samus Aran, there you have it, Samus also does not have a significant other, both single, both independent, both badasses in their own ways. Samus and Uta, author-san, make it happen and make it QUICK, time to erase Kaoru's existence of this story.
Yes, at first it was kind of cute the way Uta started out the series being much more thoughtful, reliable, and overall just more mature than the emotionally oblivious and pathologically conflict-avoidant Kaoru--it made what appeared to be the impending age-gap romance rather more understandable, not to say palatable, than such things usually are.
But Kaoru spent most of the series not getting any better, and in fact often being considerably worse than she started--had her inevitable confrontation with Reiichi happened, oh, say, 20 chapters ago, I wouldn't be so inclined to say, "Uta, run as fast as you can the other way--this woman offers you nothing except emotional co-dependency!"