I wish I could be as smooth as Paul Simon, but here are the general areas the words fell into in no particular order. Both sides would probably want to continue the relationship, but a problem or unfortunate occurrence made the situation unbearable. This is the one-sided one where one person acts and the other never saw it coming. The breaker is beyond ready and the breakee is shocked. This never, ever really happens.
Someone has to be the first one to set the wrecking ball in motion.
So that's it, at least from a college student's perspective. Yet we all for the most part strive for relationships regardless of the reality of the situation.