Alternatively Kaoru finds out that Uta is suffering too much and intervenes. Ultimately she can't do anything for herself, but her protectiveness of Uta should count for something.
Another complete course reversal by having Kaoru become effectively proactive by like, doing something.
One can always hope.
Say about her waht you want, but she at least made an effort to protect Uta. She is trying to hodl the three of them together. If something bad were to happen to Uta, Kaoru would not hesitate to help. The only thing she can't do is help herself.
I agree, tbh I think Kaoru loves more the idea of the 3 of them staying together as a family than just her and Reii, hopefully she helps herself eventually and confronts Reii eventually, to see if he was cheating or not, she'd be a lot happier with that off her chest though I think she already had/felt problems with her relationship with him, feeling rather unhappy or lonely and whatnot, I want that to be addressed too if she confronts him, so that she can understand herself better and see what she truly wants in her life.