Does a wife bear a sin and is she obliged to offer expiation for treating her husband in kind, even though the husband does not feel he has erred after causing a problem unnecessarily?

What happened between the spouses is natural and not described as a sin or transgression, unless it reaches the point of neglecting an obligatory right. Rather, the sin occurs when one of them neglects the right of the other. So, if the wife's action results in preventing the husband from his right to the bed, or going out without his permission, or disobeying his obligatory command, she is sinful, and repentance and good companionship suffice for her. Likewise, the husband, if his action does not result in neglecting a duty upon him, he is not sinful. The righteous woman does not merely suffice with performing her duties; rather, she strives to be among the best of women. The Prophet, peace and blessings be upon him, described the best of women as being loving (al-wadūd), fertile (al-walūd), and returning to her husband (al-ʿaʾūd), who says: "Here is my hand in your hand; I shall not taste sleep until you are pleased," if she is wronged.