How can one be certain of being afflicted by magic (sihr), what is the method for its treatment and getting rid of its effects, and does magic fade with time, especially in a case involving a lack of desire for marriage and social isolation after consuming food that one was urged to eat?

It is not permissible to accuse a Muslim of sorcery without lawful evidence. It is advisable to adhere to obedience to Allah Almighty and to consistently recite the dhikr (remembrance of Allah), especially the morning and evening adhkar. One may consult specialists in Ruqyah Shariyah (Islamic exorcism) while being cautious of charlatans and imposters. There is no objection to performing Ruqyah on oneself with verses for invalidating sorcery or seeking it from someone trustworthy. There is no religious evidence that sorcery dissipates with the passage of time. One should avoid saying "fate willed it" and replace it with "Allah Almighty willed it."