All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah.
A Muslim should place his trust in Allah and avoid excessive fear of jinn or surrendering to obsessive thoughts. Being afflicted by jinn possession does not mean that Satan has control over a person. Rather, Satan’s plotting is weak, and he has no authority over those who seek refuge in Allah and obey Him.
Anyone who believes that he is afflicted by possession should be keen to perform legitimate Islamic ruqyah, maintain the obligatory prayers and daily supplications, recite the Quran, and seek help from a trustworthy ruqyah practitioner known for righteousness and adherence to the Sunnah.
As for informing the fiancée about the condition: if the effects of the alleged affliction are apparent and affect married life, the man must be honest with his fiancée and her family before marriage. This ensures that the marriage is based on clarity and prevents deception or concealment. Each party has the right to make an informed decision.
Among the means of protecting both spouses from Satan are:
Maintaining the prayers, supplications, and acts of obedience to Allah.
Reciting Surah Al-Baqarah in the home.
Reciting Ayat al-Kursi and the two chapters of refuge (Al-Falaq and An-Nas).
Reciting the supplication before marital intercourse: “In the name of Allah. O Allah, keep Satan away from us and keep Satan away from what You provide us.”
If the fiancée is informed of the situation and agrees to the marriage, and both spouses seek refuge in Allah and remain committed to obedience and remembrance of Him, then it is hoped that Allah will protect them from Satan’s schemes.
One should not surrender to fear or assert with certainty that the jinn will harm the wife. The basic principle is that a Muslim should place his trust in Allah while continuing with treatment and ruqyah until the symptoms disappear, by Allah’s permission.
And Allah knows best.