live in sin vs play house

live in sin

verb
  • To cohabit as if husband and wife without being married. 

play house

verb
  • To live as if married without actually being legally married. 

  • To pretend to be a family in the household, acting out housekeeping and different family roles. 

noun
  • A child's toy domestic dwelling, either for dolls or large enough for the child to enter. 

How often have the words live in sin and play house occurred in a corpus of books? (source: Google Ngram Viewer )