An older movie about an old man, a boy and a Native American man?

I'm pretty sure the boy and the old man were white. They all are, or become good friends. All I can remember besides that is that one of the 3 dies, then another and the last joined them by committing suicide. At the end of the movie, the boy and the Native American are playing and swimming (something they always did when they were alive) in the river as the old man sits on his front porch smiling and watching them in the "afterlife". I saw this movie when I was about 10, so 40 years ago or so. Any ideas? Thanks