And though we prepare for losses in love, the end of a friendship always takes us by surprise. Often people just drift apart, but if there's a serious conflict, people take a more active role in ending it. Friendships wax and wane. Sometimes you feel close, other times less close. But there's no social framework to sustain a friendship that gets into trouble.
People start to build a case against the friendship.
Nothing forces you to try to keep it together. In fact, nothing holds relationships together but two people's goodwill, and that is often not enough. And this is as close to organized religion as you will ever find me.