Help me find the name

I saw this movie years ago. All i remember is there was a boy and a girl and they made a treehouse somewhere.there was something like a river between their home and the treehouse. The girl didn’t have any TV in her house. The girl got drowned in the river trying to get to the treehouse.oh and there was a girl bullying them so they bullied her back and the bully went crying in the bathroom. Thanks