get together vs have a thing

get together

verb
  • To start dating; to start being a couple. 

  • to agree 

  • to accumulate, to gather 

  • to meet, to gather together, to congregate 

  • Used other than figuratively or idiomatically: see get, together. 

have a thing

verb
  • To be in a casual romantic relationship. 

  • To have a crush on, or a soft spot for, someone. 

How often have the words get together and have a thing occurred in a corpus of books? (source: Google Ngram Viewer )