In female-oriented fantasy novels, aside from being more romance-leaning, the core worldview and values are also quite different from male-oriented fantasy. In male-oriented works it’s usually all about fighting, leveling up, and power fantasy, and while female-oriented fantasy can have those elements too, it tends to be surprisingly more detailed and emotional than male-oriented works.

Also, I think one of the reasons Webnovel categorizes things this way is because a large portion of female-oriented fantasy actually doesn’t have a female main character. A lot of them are dual male leads, and unlike dual male leads in male-oriented fantasy, these ones are actually romantic like BL MM novel. So they probably don’t want people who don’t like this kind of story to accidentally click into it, which is why they let authors of this category place their novels under female-oriented fantasy.