1.
If something falls apart , it breaks into pieces because it is old or badly made.
The work was never finished and bit by bit the building fell apart.
PHRASAL VERB : V P
2.
If an organization or system falls apart , it becomes disorganized or unable to work effectively, or breaks up into its different parts.
Europe’s monetary system is falling apart...
I’ve tried everything to stop our marriage falling apart.
= break down
PHRASAL VERB : V P , V P
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. ( INFORMAL )
I was falling apart. I wasn’t getting any sleep.
= crack up
PHRASAL VERB : V P