gratification vs unfulfillment

gratification

noun
  • The act of gratifying or pleasing, either the mind, or the appetite or taste. 

  • A gratuity; a reward. 

  • A feeling of pleasure; satisfaction. 

unfulfillment

noun
  • The failure to fulfill or perform something. 

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