Is a wife sinful for refusing intimacy with her husband while he is in a state of intoxication? And is it permissible for her to threaten him with separation, or by saying: "May Allah set a boundary between us if you drink," or "I will be unlawful for you"?

If you refrain from conjugal relations with your alcoholic husband because you are bothered by his smell, there is no sin upon you. However, if the abstinence is intended as a deterrent for him, most scholars do not permit it, while some allow it if its benefit is deemed probable. Your threat to leave him is permissible. However, making your relationship unlawful contingent upon his drinking alcohol is not advisable. If you utter such a statement and he then drinks alcohol, it does not constitute ẓihār (a form of divorce) or make the relationship unlawful, but it does necessitate an expiation for breaking an oath. Our advice to you is to strive in reforming your husband. If he repents, then cohabit with him in a good manner. If he does not repent, it is better to separate from him through divorce or khulʿ (a woman-initiated divorce).