How can I help a friend who wishes to convert to Islam, but has refrained from doing so because he knows about the obligation to fast, as he is addicted to drinking coffee as a treatment for migraines and headaches?

Indeed, the greatest of Allah's blessings upon His servant is His granting him success in religion and opening his heart to faith, as stated in His Almighty saying: (So whoever Allah wishes to guide, He expands his breast to Islam; and whoever He wishes to lead astray, He makes his breast tight and constricted as though he were ascending into the sky. Thus does Allah place defilement upon those who do not believe). Fasting Ramadan is a fundamental pillar among the five pillars of Islam, and whoever pronounces the two testimonies must submit and surrender to Allah the Almighty and His law.

If a headache prevents a person from fasting, they can drink coffee at night or use medication. If they experience a headache during the day and need medication, they are permitted to break their fast and make it up later, for religion is ease and not hardship (But whoever among you is ill or on a journey - then an equal number of other days). However, if refraining from coffee is due to personal whims and desires, this prevents true adherence to religion.

Allah is more merciful to His servants, and whoever approaches Him sincerely, Allah will accept from him and assist him, (As for he who gives and is righteous And believes in the best We will ease him toward ease). Repentance is open for sins, but polytheism with Allah is the only sin that Allah does not forgive (Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills). Finally, friendship between a man and a woman is not permissible in Islam.