To fall apart is to break into pieces, whether an object, a plan or a person. The book will fall apart, the deal fell apart, fall apart under the strain.
The physical and the figurative senses are equally common and equally plain. Of a person it means losing composure rather than health, which is a kinder thing to say than breakdown.
1phrasefall apartTo break into pieces — objects, plans, or people under stress.
“Cheap boots fall apart in a single wet winter.”
fall apart is a phrase.
Practised in Phrasal Verbs