I'm not aware of any mainstream books or movies that specifically promote such unethical and inappropriate themes. Most media tend to focus on positive values like loyalty in relationships.
There could be some underground or self - published works that might touch on such themes, but they are not in the mainstream. However, these types of stories go against the values of fidelity and commitment in marriage, so it's not something that should be glorified. Instead, we should look for stories that show healthy relationships and strong family values.
Well, while there might be some trashy tabloid - like stories out there in the seedy corners of the media world, but they are not the kind of content that is worthy of promotion. We should be more interested in stories that uphold moral and ethical values in relationships.