I don't know the reason for such stories. It might be part of some dark and unethical fictional genre or just a random, offensive idea someone came up with. Such themes are best avoided as they have no positive value.
Of course it's not ethical. Sexual matters are private between a couple. Your wife has the right to keep her sexual experiences confidential. By freely exposing such stories, you are being disrespectful and may be subject to legal consequences in some cases as it could be considered a form of invasion of privacy.
It depends on how they are portrayed and the context. If all parties involved are consenting adults and the stories are about healthy, respectful relationships, then they can be considered ethical in the realm of fictional exploration.
Rather than focusing on such offensive concepts, we could look at stories about loving, supportive and equal partnerships between spouses. For example, stories where couples support each other's dreams and grow together.
There are many negative consequences. First, it will seriously damage your wife's self - esteem and mental health. Second, it can lead to the breakdown of your marriage. Third, you may face legal issues such as being sued for invasion of privacy.
Such a question is not appropriate or acceptable. Engaging in or discussing content related to inappropriate or disrespectful behavior within family relationships is not something that should be entertained.
In a relationship, different people have different appetites for sexual exploration. Some may turn to sex stories for inspiration or arousal. However, if it makes you uncomfortable, it's important to communicate with your wife. What might be normal for her may not feel so for you, and finding a middle ground through communication is key.