Why do Opal and her father go back to the party when they're looking for Winn-Dixie ?

Opal and her father do not return to the party until later. Her father wants to return, but he changes his mind after Opal tells him that he gives up too easily.... that he gave up on her mother, that he doesn't see things through. Preacher is reduced to tears by his daughter's words, and he expresses his grief over her mother's leaving.... and Winn Dixie's disappearance. The two make amends and call out to Winn Dixie as they walk back to town. When they near Gloria's, they hear music playing and go to the house, where everyone is still happily celebrating. Opal is angry that everyone continues to have a good time while Winn Dixie is missing.... only to learn that Winn Dixie had never gone away.... frightened of the thunder, he'd run under the house.