Retro Gaming<br>Clint loved playing classic games from the 1980s. His dream was to own an original Pac-Man arcade cabinet. His family built him a replica for his birthday. Clint loved it and thanked his family profusely. Inside Clint felt a pang of ingratitude at it being inauthentic.
Clint felt ungrateful for his birthday gift. 
Clint felt ingratitude at his birthday gift being inauthentic therefore he was ungrateful, which is a related term to ingratitude. The two different terms probably confused the system.