fool around vs have an affair

fool around

verb
  • To engage in casual or flirtatious sexual acts. 

  • To engage in adultery; to play around. 

  • To waste time. 

  • To engage in frivolous behaviour; to monkey around. 

have an affair

verb
  • To engage in a romantic or sexual relationship while being married. 

How often have the words fool around and have an affair occurred in a corpus of books? (source: Google Ngram Viewer )