Our MC will probably take the knife for her, someone will witness all this bs and call the cops and an ambulance, she cries for him and then he either dies or he recovers and they live happily ever after and make babies idk. I'd prefer if he lives because the FMC might commit sudoku otherwise. Or maybe the FMC will be threatened by that crazy bitch and will go home with her. If that's the case then we can expect her get beaten up until she's nearly dead.
Man, I just wanted a happy ending for them both.