make a move vs slope off

make a move

verb
  • To depart from a place; to set off. 

  • Used other than figuratively or idiomatically: see make, move. 

  • To take action. 

  • To initiate a conversation or perform an action intended to engage the willing attention of a person in whom one has a romantic or sexual interest; to approach someone of romantic or sexual appeal in hopes of escalating to a romantic or sexual encounter or relationship. 

slope off

verb
  • To depart quietly, without being noticed. 

How often have the words make a move and slope off occurred in a corpus of books? (source: Google Ngram Viewer )