Nothing is more traumatic than seeing a relationship falling apart. It breeds suspicion, distrust and distance. A couple who could not live without each other at one point of time start finding reasons to stay away. The relationship failure is painful for both the partners. Both try to hurt each other; and the more they hurt each other the more they destroy what was once a very loving relationship.
It takes a long time to build a relationship. But it does not take long to destroy it. In fact, the cycle of failure needs no pushing; it gathers its own momentum. And once it does so, it becomes very difficult to stop it or put it in reverse gear.