1 - If
something falls apart, it breaks into pieces because it is old or badly made.
2 - If an organization or system falls apart, it becomes disorganized or unable to work effectively, or breaks up into its different parts.
3 - 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.
Ex1: "The work was never finished and
bit by
bit the building fell apart."
Ex2: "I guess it was like that for you when your company started to fall apart."
Ex3: "I was falling apart. I wasn't getting any
sleep."