How does a community fall apart?

A community falls apart when the things holding them together are cut, or no longer exist. There can be any number of things holding them together, including jobs, religion, family, or other community groups or social issues.

Alternately, communities can fall apart if something divisive overwhelms the things that hold them together. Eg, some common issues include gay marriage, abortion legalization, crime, drug use.

Often one group of people put down another group of people, when in fact the two groups are not that different. This dehumanizing of one group leads to rifts in the community, which often escalate.