I only remember fragments of it, but I remember that there were siblings (I think), a young boy and an older girl that live in a dirty house in either a small town, or in the middle of nowhere. One particular scene where the boy plays with some old stuff is also worth mentioning, i feel like it was the house of their mother.
In one scene it looks like the girl is making advances on the boy.
In the end the girl leaves her brother alone. He runs looking after her, but doesn't find her. There were probably fireworks also.
It is probably an indie movie, and the quality reminds me of the 90's or early 2000.