Okay this Fuuko girl is kinda crazy, she seems like someone who didn't get much attention as a kid and now does these things. Kinda of a psycho there for sure, stalker and all
About the cheating, it almost seems like Yuni was half-wanting that her GF called her on a date and half-waiting for an excuse to cheat on her, Idk really, it could be a so said "moment of weakness" but she's wrong total imo
And Nanase, she is kinda inconsiderate of her GF's feelings, but I don't think it justifies being cheated on. Maybe it would not have happened if she gave nore attention to her, but maybe Yuni would cheat anyway so idk
Eager to see what happens next anyway, interesting story