Unfulfilling is a word that is used to describe something that doesn't give you the satisfaction that you were hoping for. Often, people use the word to describe jobs, relationships, or life in general.
His job is unfulfilling because he doesn't get the satisfaction that he was hoping for.
The relationship is unfulfilling because it's not fulfilling the expectations that she had.
Her life is unfulfilling because it's not what she expected it to be.