girlfriend vs other man

girlfriend

noun
  • A female partner in an unmarried romantic relationship. 

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

  • A female friend. 

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

other man

noun
  • A man who is romantically involved with someone (usually a woman) already in a committed relationship with another man, especially a man having an affair with a married woman. 

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