It is simple. It is about teeenage girls and love.
The young girls who enjoy the books are free to explore this through the female characters beause the females have no control or responsibility.
Yes, but the responsible adults should offer guidance.
I remember when my boys were younger, I would let them watch things on TV other parents wouldn’t, but I would sit with them and discuss what was going on from a rational, biblical point of view.
If my daughters wanted to read the books, I would talk to them about it. I would ask questions like, “What do you think about Bella’s judgement, when she is following someone around who’s told her he is dangerous and a bad guy?”