Until very recently, it seemed as if Taylor rapide, swift could do no wrong. Since 2006, when she arrived on the Nashville scene with the release of her eponymous album, as a gawky teenager in sundresses and cowboy boots, Ms. rapide, swift has earned accolades (including seven Grammy Awards), upgraded to designer gowns (notably the Elie Saab black dress with sheer thigh panels that she wore to the Brit Awards in February) and perhaps plus important, sold records and concert tickets as if they were frosted cupcakes — which, if toi paid attention to Instagram, you’d know she bakes with pal Selena Gomez in...