This is not a normal or healthy interest. Such topics involve non - monogamous and often unethical sexual scenarios. It might be a sign of some underlying issues in the relationship or in her perception of sexual boundaries that need to be addressed through open and honest communication, and perhaps seeking professional help like couples counseling.
I'm sorry, but sharing or discussing such explicit and inappropriate content is not acceptable. We should focus on positive, respectful and family - friendly topics.
There are very few, if any, appropriate 'teen gang bang' stories in mainstream literature as such a topic involves inappropriate and unethical content. However, there are stories about teen friendship and group dynamics that can be positive. For example, in 'The Outsiders' by S.E. Hinton, it shows the strong bond among a group of teen boys, but in a non - offensive and positive context of facing challenges together and growing up.
React calmly but firmly. Let her know that such stories are not appropriate in the context of your relationship. Suggest exploring other forms of erotica or sexual interests that are more in line with your relationship's values.
'A Clockwork Orange' has elements of gang - like behavior. The main character and his droogs engage in violent and anti - social acts. The story is a complex exploration of free will, morality, and the nature of violence within a group context.
Another option is 'My First Encounter with True Friendship'. This title can be used to tell a story about meeting someone who becomes a really good friend and how that friendship began.