pet vs the object of one's affections

pet

noun
  • Something kept as a companion, including inanimate objects. (pet rock, pet plant, etc.) 

  • One who is excessively loyal to a superior and receives preferential treatment. 

  • A fit of petulance, a sulk, arising from the impression that one has been offended or slighted. 

  • An animal kept as a companion. 

  • Any person or animal especially cherished and indulged; a darling. 

  • A term of endearment usually applied to women and children. 

verb
  • To stroke or fondle (another person) amorously. 

  • To stroke or fondle (an animal). 

adj
  • Favourite; cherished; the focus of one's (usually positive) attention. 

  • Kept or treated as a pet. 

the object of one's affections

How often have the words pet and the object of one's affections occurred in a corpus of books? (source: Google Ngram Viewer )