It's one of my favorites from the box set. And taking the words literally, it is either the end of a relationship due to one of the people falling out of love - or the end of a relationship due to the actions of the singer. We don't know what those actions are (or were) but there are several references to them:

"Sometimes heroes have to lose"

"I always told you that a man has got to face his own mistakes
Sometimes you get a lucky break
Sometimes your winning streak will stay
Sometimes you gotta pay"

The river is of course life's driving force itself.

And this song contains one of my favorite quotes ever:

"Everybody goes with the fire in their eyes" which in my book says an awful lot in a few well chosen words. Some people's fire burns hotter than others.