What is the ruling on a husband entering an apartment that his wife swore was forbidden to him, like his own mother, if he entered it, and what does he owe for that?

What happened is that the wife's prohibition was made contingent upon her entering the apartment; if she enters, the prohibition takes effect. The predominant view regarding the prohibition of a wife is that it refers back to the husband's intention, whether he intended divorce, zihar, or an oath. It is recommended to control anger and beware of its consequences, and to adopt calm dialogue as an approach for understanding in marital affairs, avoiding solving problems with words like "prohibition" and the like.