Are recurring sexual fantasies about other people, despite a girl's love for her fiancé, normal, and what is their interpretation and treatment? Do they indicate a lack of love for her fiancé, a mental illness, or a malicious whisper from an evil soul?

Love between young men and women is not permissible in Islamic law except within the framework of marriage. It is permissible for a man, when intending to marry, to look only at the woman's face and hands, based on the saying of the Prophet, peace and blessings be upon him: "If one of you proposes to a woman, and he is able to look at what would encourage him to marry her, then let him do so." And based on the Almighty's saying: "Tell the believing men to reduce [some] of their vision and guard their private parts. That is purer for them. Indeed, Allah is Acquainted with what they do. And tell the believing women to reduce [some] of their vision and guard their private parts and not expose their adornment except that which [necessarily] appears thereof." It is not permissible to look at other parts of her body.