“I didn’t know / How deep some feelings can go,” confesses Esperanza Spalding on this enchanting, empathic effort from her Songwrights Apothecary Lab. “And you can really do some damage down there / In the soul of another.” Taking honest measure of her own failed obligations in a romantic partnership, and crucially resolving to do better, Spalding has made a delicate yet durable song out of that rarest of modern human instincts: accountability.