What is the ruling of Islamic law regarding a husband who ejaculates merely from normal conversation with his wife with whom he has a marriage contract, without sexual intercourse or provocation from her, and is she sinful?

There is no harm in the husband enjoying and finding pleasure in his wife's words before consummation, even if it leads to the emission of semen, as long as there is no action from him that causes it, such as touching the thigh or hand, for that is considered prohibited masturbation.