Responses

Might be that she thinks the whole girlfriend/partner and the fact that he started to behave was just an excuse to keep the apartment and go fool around with people of different genders without getting caught and therefore she ain't against the fact that he was with a boy but she's pissed his sleeping around. At least that's what I hope, also it can be possible it's this and not that they're homophobic since she had never fully believed he was dating one person only
how come she can say that when back then, she was complimenting the said 'girlfriend' for setting Jaehyuk straight for once?? so when it's a guy, Jaehyuk's standard have now become so low? i hope she's just joking :((((