A married woman whose husband prays but uses narcotics, and he promised to quit them gradually; what is the ruling on her remaining with him?

Questions and answers over the phone.

The Shaykh : Peace be upon you
Abu Layla: And upon you be peace. How are you, our Shaykh?

The Shaykh: We praise Allah and give thanks to Him.
Abu Layla: I am well, if Allah wills.

The Shaykh: I am always well, Abu Ahmad.
Abu Layla: May Allah bless you. Praise be to Allah.

The Shaykh: Of course, goodness varies.
Abu Layla : Yes.

The Shaykh : Praise be to Allah.
Abu Layla: My Shaykh, there is a woman whose husband, after Allah turned her to repentance and she came to know the truth, was addicted to narcotics. So when she came to know the truth, she said to him: either you quit these narcotics and repent to Allah and pray, or there will be separation between you and me.

The Shaykh : Very good.
Abu Layla: But the woman loves this man very much.

The Shaykh: How.
Abu Layla: The woman loves this man very much, and the husband also loves her very much. So he promised her that he would quit the narcotics, but in stages. She said to him, "No, I want you to cut off the narcotics completely." He said, "I cannot." So what is the ruling regarding this woman, my Shaykh? He promised her, and Allah knows best that he prays, but he uses narcotics.

The Shaykh: By Allah, this requires detailed knowledge. First, what type of narcotics? Second, what is the quantity? Third, what is the proportion of the promise he is making to her? And finally, if we assume that she has knowledge of the proportion of narcotics he uses daily, and if we assume this, and he promises her that, for example, within a week he will limit himself to half of what he was addicted to; then they agree on a system and a methodology. In that case, she may agree to remain with him. If she feels that he is sincere in keeping his promise, she remains in his marriage bond; otherwise, she insists on separation.