The story was all over the place. I didn't find it to be particularly funny, sweet or romantic. Moreover, I hate when stories use sexual assault for comedy.
Yukiko was weirdly passive and was sending all manner of mixed signals. She was pretty selfish and I loved the comments Mirino made about her. Fuuko was supposed to be her oldest friend whom she shared a special bond with - only feeding on her for ten years and having some sort of unspoken love. Well, she sure didn't act like it. She really didn't show much affection to Fuuko at all. I considered her hooking up with Konomi to be borderline cheating, even though she wasn't officially in a relationship with Fuuko. And her not stopping the sexual advances of Konomi at the pool was just weird. I thought the bite mark on her but would be important, but the story was probably cancelled. I didn't feel her choice at the end was sweet or particularly rooted in any deep love. She was so indecisive until the very end. It was more Fuuko making a choice.
Konomi was manipulative. She lied. She tried to break a relationship for her own selfish reasons. She didn't even remotely care about consent. She acted like a proper succubus.
Fuuko I understand. She thought her and Yukiko shared a deep bond and was deeply disappointed in Yukiko. Her jealousy got the better of her in the start, but once she made up her mind she was pretty much willing to do anything for Yukiko. Even ignoring stuff like the bite mark on the but. I wouldn't say Yukiko earned her devotion.