Complex sentence: She suspects that the tale started out as a popular myth, or intentional defamation presumably tailored by Emma of Normandy, the other wife of Cnut and rival to Ælfgifu.
Split into simpler sentences: She suspects that the tale started out as a popular myth, or intentional defamation. Presumably tailored by Emma of Normandy, the other wife of Cnut and rival to Ælfgifu.