Well Rachel had a compelling reason and MrDot could do something with her, like a side story or a sequel, eh he could even do a prequel to how D and Rachel got divorced.If I was in the authors shoes I'd have started another story. Something more on the line of can F protect D from bad shit.
Another option would be the down fall. That's going to be rather unpopular though. The characters haven't really done anything bad to anyone else for people to root for their demise. Even if you did create a compelling reason for people to hate them you are preying on the more base of instincts to sell the story. That isn't going to do anyways as well as father protecting daughter.
To be clear my personal opinion is the author should stretch his legs and move on to something new and fresh rather than keep trying to milk this.
She was a fucking bitch, but i loved her character, she was rich with personality and a full range of emotions, for that reason i would download and play anything with her in it, but one chapter only, please.