Poems About Ungratefulness
This one about forgetting the help which you once relied on to succeed. More readings: 教育百科 奇摩知識 


  筌者所以在魚，得魚而忘筌；蹄者所以在兔，得兔而忘蹄；言者所以在意，得意而忘言。
  《莊子·外物》


If you are interested in fable prose as well, 《中山狼傳》is a pretty good one. As a matter of fact, 《紅樓夢》once quotes 《中山狼傳》to describe ungratefulness. More readings: 詩詞網 百度百科 互動百科 奇摩知識


  子系中山狼，得志便猖狂。金閨花柳質，一載赴黃粱。《紅樓夢》