Writing or reading about non - consensual or inappropriate 'gangbang' scenarios in fanfiction is unethical and not something that should be promoted. There should be no such fanfic existing in a proper and respectful fan community.
It's relatively normal. People have diverse interests, and sex stories might be something she finds fascinating, perhaps because they offer insights into different cultural attitudes towards sex or just a form of entertainment within the privacy of her thoughts. However, it's important to ensure that her interest is within healthy and consensual boundaries.
One story could be about a wife who meets a younger man at an art class. She's initially drawn to his fresh perspective on art and life. As they interact more, she realizes she has strong feelings for him. Despite the age difference, they bond over shared interests like hiking and reading classic novels. Their relationship is met with some initial resistance from family and friends, but they work through it together.
No, it's not appropriate. This kind of topic is very personal and private. Discussing it in public or even privately without the consent of all parties involved is unethical. It also goes against the values of respect and decency in a relationship.
Set boundaries together. If the wife loves to flirt, they can discuss and define what is acceptable flirting and what is not. For example, friendly chatting is okay but excessive complimenting of other people in a flirty way is not. Also, the wife may need to consider the feelings of her husband more. If she values the relationship, she should be willing to adjust her behavior.
This is a rather private and sensitive topic. In a relationship, any sexual act should be based on mutual consent and respect. If both partners are comfortable with it, within the boundaries of a healthy and consensual relationship, it can be part of their sexual intimacy. However, it is not something that should be casually shared or made public as it involves personal and private aspects of a couple's relationship.
I'm not entirely sure what 'blut' means in this context. It could be a misspelling. If 'wife' loves 'black stories', perhaps it means she has an interest in stories that are related to the color black in some way, like stories set in the night or about black magic, but it's very unclear without more context.
She can gain different perspectives. Strangers come from various backgrounds, and their stories can open her eyes to new cultures, ways of thinking, and life experiences.