My wife had been reading romance novels for decades and I decided to see what she was reading and in those harlequin novels silouette and dozens of others I found that the they were romance filled with sex (Porn)three to four sex scenes in a story each more intimate then the last-- far from romance the stories were about getting what the woman wanted emition money power fame and would do whatever was necessar to that end.
Over time she became complete disfunctional and was sucked in by the novels fantasies and feelings -- she became massively depressed -- refused treatment and meds, and then one day deserted me and her children.
I don't totally blame it on the romance novels she read but that became a major source of input and stimulous for her while real life family and friends became so much less to her she needed her daily romance novel fix.
Before she left she got introduced to anime and she had a feeding frenzy on the emotion of cartoon characters. So when she needed more of a fix she became sucked into gay anime and anime porn.
I can say that it was clearly an emotional addiction on her part, she continually needed larger and more potent doses until she was cloistered in her room night and day by herself perched in front of a computer.
Notch by notch she channged from a Church going Christian to a hedonist -- she went from being atuanch conservative to a liberal. I wish I could say it wasn't true and I confess I miss the woman that I married in bible school who had a heart for the Lord -- And my children greatly miss their mom too.
Don't confuse the symptom with the cause. While I do feel for your loss, I do not think what happened to her is the romance novels fault or that it was some demonic entity that sucked her downt he wrong path. She probably used that stuff as an escape, and just like any escape if you find the proble she is escaping from, the elephant in the room that is causing her so much emotion damage and making her unstable then you would probably fix the problem with the books. Normal sane people do not do what you are saying your wife did, they do not toss everything aside for a book or a feeling. Only people with severe emotional problems do this sort of thing. And as is the case with all sever emotionally traumatized people, if you take away the symptom i.e. the books she will only look for her fix some where else because her pain is still there and it needs to be numbed.