break off vs split up

break off

verb
  • To end a relationship. 

  • To end abruptly, either temporarily or permanently. 

  • To remove a piece from a whole by breaking or snapping 

split up

verb
  • Cease to be together, break apart from the group. 

  • separate, disassociate, cause to come apart. 

adj
  • Divided or separated. 

How often have the words break off and split up occurred in a corpus of books? (source: Google Ngram Viewer )