We don't get the whole story but I'm guessing daun dated her for only sx and the red hair girl feel neglected and cheated
I'm not sure yet if it was just for sex but definitely the other girl felt in some way neglected or something similar and then she cheated but still
This was my guess as well. But like a classic narcissist, red head only focuses on the wrongs she perceives Daun did to her while conveniently ignoring facts like her choosing to cheat rather than discuss their problems together first (according to Daun’s recollection anyway). The way she attacks Daun unprovoked with all the malicious name calling makes me think she really believes she did no wrong triggers me! …..ugh! (╯°Д °)╯╧╧
Wait wait that girl cheated on her and acts like that?