Pippa was already waiting at their "spot"—the same square meter of grass they had shared for the last eight years. As he approached, the air filled with the sounds of their unique language: rhythmic bill-clapping, sky-pointing, and gentle "mooing." The Courtship Dance
The friendship/romantic tension between Tod and Copper dissolves because Copper has been bred to kill foxes. The line, "We gotta be friends forever, right?" followed by "Yeah, forever," is devastating because the audience knows instinct will betray love. This is a quintessential "doomed relationship."