What is the legitimate Islamic way to solve the problem of a husband's oath not to greet his wife's brother, and another oath to divorce his wife if she opens the door for her brother, and how can the relationship between them be improved?

If a husband swears an oath of divorce that his wife will not open the door to her brother, and then wishes to retract it, he cannot retract a conditional divorce according to the majority of scholars, and this is the preponderant opinion. Rather, the condition upon which the divorce was suspended must not occur. However, if the condition occurs and the husband breaks his oath, he can take her back.

Regarding the method of reconciliation between the two parties, they should be advised about the seriousness of a Muslim forsaking his brother for more than three nights, and that the better of them is the one who initiates the greeting, and that whoever forsakes his brother for a year is as if he has shed his blood. Efforts should also be made to reconcile them, especially by people of virtue and righteousness, due to the great reward in it and in compliance with Allah's command to mend relations.