Sarah finds a magical notebook from the Awesome Store that makes whatever she draws come true. She begins drawing bizarre "ships" (romantic pairings) between the residents of Elmore, leading to absolute chaos as the townspeople are forced into ridiculous relationships.
Below is a guide for that specific episode and a few other possibilities that match your description. Overall Episode Number: 210 (Season 6, Episode 14). Watch S6Ep 210
You can typically find this on Hulu , the Cartoon Network App , or available for purchase on platforms like Amazon Prime Video and YouTube. Family Guy: "No Country Club For Old Men " The Shippening - The Amazing World of Gumball Wiki Sarah finds a magical notebook from the Awesome