It seemed like the trailer was for a different version of the film. The final cut must've changed the story because what was promised appeared to only be on screen for a few minutes.
The protagonist isn't somebody you can really connect with as she always seems hostile and ungrateful towards others. That makes it difficult to root for her or feel sad for what happens to her. And when the trailer's story finally starts, it abruptly ends - but doesn't end the movie, which somehow keeps going and really ends, but abruptly once again.
The writers or director seemingly had trouble deciding when and how to end the film. It feels like there was an idea that developed, changed and somehow didn't fit with the beginning.
All in all, I was left with an annoyed feeling and a "wut?" face.