What is the ruling on a marriage that took place through magic, and does it invalidate its legitimacy? Also, what is the interpretation of a sister seeing her husband in a dream after she complained of jinn possession and suspected that he was the one who bewitched her into marrying him?

It is not permissible to accuse anyone of sorcery without clear proof, just as it is not permissible to consult diviners and soothsayers, because whoever consults them and asks them questions, their prayers will not be accepted for forty days, and whoever believes them has disbelieved in what was revealed to Muhammad, peace and blessings be upon him. There is nothing in Islamic law called "Istikshaf prayer" for uncovering the unseen; these are superstitions of sorcerers. Your sister must repent and not pay attention to these superstitions or dreams. One should not exaggerate in attributing problems to magic or possession; rather, apparent causes should be examined and treated by lawful means. If there is evidence of sorcery, its cure lies in reliance upon Allah, persistent remembrance of Allah (dhikr), lawful ruqyah, and having a good opinion of Allah. Sorcery does not affect the validity of marriage; if a marriage fulfills its pillars and conditions, it is valid.