come apart vs split up

come apart is not a noun while split up is a noun.

Word	Noun	Adjective	Verb	Adverb
come apart	No	No	Yes	No
split up	Yes	No	Yes	No

As verbs, come apart and split up are synonyms defined as:

Other synonyms of come apart include break, fall apart, separate.

come apart (noun)	split up (noun)
	an increase in the number of outstanding shares of a corporation without changing the shareholders' equity

come apart (verb)	split up (verb)
become separated into pieces or fragments	become separated into pieces or fragments
	get a divorce; formally terminate a marriage
	discontinue an association or relation; go different ways
	separate into parts or portions