Real Dictionary

fall apart
phrasal verb: If an organization or system falls apart, it becomes disorganized or unable to work effectively, or breaks up into its different parts.
phrasal verb: If something falls apart, it breaks into pieces because it is old or badly made.
phrasal verb: If you say that someone is falling apart, you mean that they are becoming emotionally disturbed and are unable to think calmly or to deal with the difficult or unpleasant situation that they are in.

fall apart in American English
to crumble, disintegrate, disunite, etc.

fall apart in British English
to break owing to long use or poor construction