What is the legitimate stance regarding a betrothed woman's insistence on seeking divorce due to fear of repeated sorcery, despite assurances of its disappearance, and her lack of faith in Allah's divine decree and destiny concerning this matter?

Divorce applies to a wife, not to an engaged woman. A woman is not permitted to seek a divorce except for a legitimate Shar'i reason. Fear of harm does not contradict belief in Divine Decree. One who fears harm should seek Allah's help and protection, and reflect on His saying, "And they cannot harm anyone thereby except by permission of Allah," and His saying, "Say: 'Nothing will befall us except what Allah has decreed for us.'" It is advised to try and convince her to perform Istikhara (prayer for guidance) and entrust the matter to Allah, and to let some people of sound judgment and wisdom influence her. If the marriage takes place, then praise be to Allah. Otherwise, he should rely on Allah and seek someone else, for there might be good in the matter that a person may not perceive.