It probably won't unfortunately. You can just see the stuff Mary says as an error on my part since I messed up the variables for the first beta ( that's why the choices won't be saved , hence the warning in the main menu ).Hmm.. Not sure I can remove, but, I can add the fsuckdick = false. Hopefully that will fix it.
If you just progress normally you will see that MC will start to disobey her though. If you really really don't want any interaction with Fiona you can of course just say no when MC overthinks everything in the night. This way you won't ever do anything sexual with her again.