@8roku I kinda have to agree with you there. I am sympathetic that she gets cheated on and that she's getting picked on at work but I do feel at this point the MC isn't really taking personal responsibility for anything. With her frequently showing up late, doing poorly on her reports and other behavior I can see why her supervisor would take issue with her. Why is she not getting her act together if she doesn't want to deal with that? Its not nice getting compared to the other female worker, but if she was at least doing her best at work she'd have a basis to defend herself.
I can understand (though I might not agree) with her still trying to get her boyfriend back because it's probably not easy for her to instantly drop her feelings for him, it just doesn't work that way. That said, she's fallen into the trap of only blaming the other woman without acknowledging his culpability. I think the true issue is likely that she's caught up in a fantasy of their relationship. Again with a high schooler mentality, she's wrapped a lot of her life and confidence around having him as her bf to the point I think she became subconsciously over confident and negligent.