On July 26, Juana Rivas, a mother of two from the southern town of Maracena (Granada, Andalusia), immersed in an international custody battle over her two children with their Italian father, absconded with her offspring after being ordered by a court to hand them over.

She disappeared for nearly a month and chat shows and news bulletins across the country wondered where they were or what the merits of the case might be. Ms. Rivas benefited from the vociferous support of left-wing politicians and feminists.

Her core argument is that Mr. Arcuri is culpable of domestic abuse and that it ...