have a thing vs lovebird

have a thing

verb
  • To be in a casual romantic relationship. 

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

lovebird

verb
  • To express romantic affection openly. 

noun
  • Any small parrot from one of the nine species within the genus Agapornis. Sometimes they are kept as cage birds and are noted for their affection towards each other. 

  • One of the members of an openly affectionate couple. 

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