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.
No. These stories are not appropriate as they objectify and demean women. They promote an unequal and often disrespectful view of relationships, which goes against the values of equality and mutual respect that should be present in healthy relationships.
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.
Rather than using offensive language, we can consider 'Stories of my equal and harmonious marriage'. This promotes healthy relationships and positive values.
The stories might also add an element of playfulness. If she tells fictional stories related to her submissive role, it can create a more light - hearted atmosphere in the relationship. They can also be a way for her to express her feelings and needs in a non - confrontational way.