WWYFF stands for Who Would You Fall For?. They can also be called WWFFY (Who Would Fall For You?). Unlike Choose Your Own Adventure books, instead of branching out completely with lots of different endings, each response usually increases the relationship with one of the love interests - or equivalent characters - in the story. Big, branching WWYFF's are not entirely undefinable, however.
They are interactive fiction stories commonly written in the form of a quiz, similar to a Choose Your Own Adventure story or a dating sim game. In these stories, the protagonist (usually a self-insert, since WWYFFs are generally written in second person) is often given a range of responses to events in the story. The most common type of WWYFF involves a reverse-harem type situation (one female character and a group of male characters), but other types do exist on a smaller scale.
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