What is the Shar'i ruling on dealing with a wife who is constantly miserable and exhausted, disobeys her husband in bed, and denies his kind attempts to make her happy, especially given the presence of a nursing infant? Is marrying another permissible, or is divorce better, particularly since her family supports her in this behavior?

Each spouse has the right to companionship in a good manner.

The wife must acknowledge her husband's status and his great right over her. It is not permissible for her to refuse his invitation to bed unless there is an excuse; otherwise, she would be considered defiant (nashiz).

The treatment for defiance is as explained by the Sharia. If the wife does not rectify her behavior, it is better for the husband, if he is able to be just, to marry another woman while keeping the first wife. Divorce is permissible, but it should not be resorted to except for a benefit, especially when there are children. It should be noted that ingratitude towards one's spouse is forbidden.