What is the ruling on a married man's heart becoming attached to another woman who is not his wife, and his speaking with her weekly?

Islam does not approve of a relationship between a man and a woman who are not married to each other. If an emotional attachment to a foreign woman arises due to negligence regarding the boundaries of Sharia, then the person is sinful and must strive to free himself from it. However, if the attachment occurs unintentionally, there is no sin, but the only legitimate path is marriage. Until the marriage contract, the relationship remains as between strangers.

It is obligatory to repent and cease communication with the woman. If you desire and are able to marry her, there is no objection. If you are unable, then you must eliminate this attachment by severing the relationship, occupying your time with beneficial activities, strengthening your connection with Allah, and lowering your gaze. Lowering one's gaze helps a husband be content with his wife, while letting it loose makes him disinterested in her and opens the doors to temptation.