If you are looking for stories with this specific premise, you can find various examples in the following formats:
If you are looking for a story with a "useful" or moral lesson rather than an adult theme, you might consider reframing the search toward or coming-of-age stories that involve navigating boundaries and respect within new family structures. seduced by his stepmom
: Many online creative writing communities host "taboo" or "forbidden" romance stories where these dynamics are the primary focus. If you are looking for stories with this