dalliance vs sex partner

dalliance

noun
  • A sexual relationship, not serious but often illicit. 

  • Playful flirtation; amorous play. 

  • A wasting of time in idleness or trifles. 

  • A episode of dabbling. 

sex partner

noun
  • Someone that one has sex with, especially on an informal or casual basis. 

How often have the words dalliance and sex partner occurred in a corpus of books? (source: Google Ngram Viewer )