Brige to Terabithia

In this book (or film) Aron meets a girl who insists he should use his imagination more, so they pretend that they are in a whole new world after they cross the old swing across the stream.

The parents once or twice mention that that swing is getting too old and mouldy for them to swing on every day. But still they swing on it to get across to Terabithia.

In the end the second main character dies.

So if you cry when a story character dies don't watch the rest