S13E11 : The Bart Wants What It Wants

Bart befriends Rainer Wolfcastle's daughter Greta. She has a crush on Bart, but he does not seem to realize it and eventually stops seeing her. Seeking revenge, Greta begins dating Bart's best friend Milhouse, which causes Bart to start missing her. She leaves for Toronto with her father, and Bart convinces his family to follow them there.