Smiles said:
girls, not women. girls love twilight.
women love vampires.
vampire literature is typically heavy stuff.
Young girls don't care for heavy literature.
Twilight is light literature (I use the term literature loosely, I'm aware, some people have strict standards for what can be called literature.. I don't, it's just a word).
Twilight is about Vampires
Young girls like light literature, and perhaps for reasons they don't quite understand, they like vampires.
Hence, young girls like Twilight.