There is no story, except the fact of boy saves girl
Way too over-rated, the movie depends on visuals and music to create emotion. It doesn't use the the semi unique circumstance/problem the MC had created for himself. Instead of addressing the self destructive nature of the MC, it uses it's poorly defined supernatural powers for both problem and solution. Not to mention the incredibly shallow character development that don't act like humans (in the real world at least) despite in a detailed world.
If you were to ask what the take-away of the movie is, the best answer you can give perhaps is "To not rely on unknown things (supernatural powers) without knowing the consequence".
What makes a story interesting is seeing a struggle for a solution within the rules it had set. This movie hadn't established any of that, making it impossible to be invested. Plus they were never in real danger in the first place since they were both underage.