Chipper's Wife has never physically appeared, but rather mentioned in the dialogue with Chipper and Tyke.
Ever since Chipper has married her, she has been making pies, pies that are often too big and too wide. At one time, after Tyke was born, she fell into her own pie. Chipper ate the pie, before realizing what he had done. He stuffed her after that, but there appears to be no stuffed animal in the house.