Is it permissible for a wife to refuse marital relations and tie it to the condition that her husband writes a document in which he commits to divorcing her if he does not treat her as she wishes, and what is the Islamic ruling on this document?

If you write a paper promising to divorce your wife if she treats you contrary to your wishes, your failure to abide by this commitment does not constitute a divorce, because it is merely a promise of divorce, and it is not obligatory to fulfill it.

We advise against writing such a paper. Instead, live with your wife with kindness, and clarify the obligation of her obedience in what is good, and the impermissibility of her refusing the marital bed without an excuse; otherwise, she would be sinful and disobedient (nashiz), and her right to maintenance would be forfeited.

If the wife does not obey, then pursue means of reconciliation with her. If her family is corrupting her, you have the right to prevent her from visiting them and to prevent them from visiting her as long as they remain in that state. If the means of reconciliation are not effective, then divorce is the last resort.