A relationship coming to an end (breakup, divorce, separation, etc.) can represent:
An actual breakup, or a fear, expectation, or curiosity about the possibility of one
The end of a phase in a relationship or friendship (but not an actual breakup), such as when two high school people go to different colleges and their relationship becomes a long-distance one
The end of a phase of interaction, such as a work-team disbanding after a project is finished, or a sports team going their separate ways after the end of the season