I’d say Kaoru is currently missing her husband; Uta basically fulfilled all of Kaoru’s needs (other than the sexual ones) and now Kaoru is realizing that she had a de facto husband alongside her de jure one.
The only displays of romantic affection from Reiichi I can remember are their date for Kaoru’s birthday and Reiichi trying to get a Christmas Eve nookie and getting turned down; for the former, he initially blew her off because of work, and even then, Reiichi only kissed Kaoru because she was practically begging for affection. Reiichi may be aloof, but at this point I’m inclined to believe he is completely uninterested in Kaoru despite caring for her.
Regarding Risako, I just can’t read her as malicious enough to want to harm anyone directly. My reading of her intentions lies more along “Kaoru and Reiichi are married, if they can go on to form a happy family and live happily ever after then that’s great. I’ll just steal Reiichi away from time to time for a date, or maybe even a small holiday, not like there’s much difference between staying late for work and going on a business trip anyway.”