friend with benefits vs girlfriend

friend with benefits

noun
  • A friend with whom one has a casual sexual relationship. 

girlfriend

noun
  • A fellow gay man, especially a friend as opposed to a sexual partner. 

  • A female partner in an unmarried romantic relationship. 

  • A female friend. 

  • A term of address for a female friend or among gay men. 

How often have the words friend with benefits and girlfriend occurred in a corpus of books? (source: Google Ngram Viewer )