What should I do about my friend whose treatment of me changed after I was the cause of his commitment to prayer and memorization of the Qur'an?

To address the alienation between you, gently ask him about its cause and clarify any misunderstandings. We advise both of you to fear Allah and avoid sins, for perhaps the alienation is due to a sin. "No two people love each other for the sake of Allah and then are separated except due to a sin committed by one of them." We also advise you to think well of your brother, for perhaps he is going through a hardship that has affected his behavior.