It is not a matter of blood relations that one close relative will treat another close relative equally. If he protects, he will protect A, and if he uses it well, he will use it well, such stubbornness is undesirable. This is normal. It is obligatory, even if someone breaks the relationship, he will continue to protect it. The Prophet (peace and blessings of Allaah be upon him) said that the one who protects the son is not the one who uses the same. Rather, he is the merciful protector of the boy, the one who protects it with the one who snatches it.
If this severance and boycott is not for the sake of Allah, in the way of Allah and for the real truth, then this is the case. Otherwise, the great way to strengthen the faith is to love Allah, to separate envy from Allah.
The Prophet (peace and blessings of Allaah be upon him) and his Companions severed ties with those who were left behind in the Battle of Tabuk for fifty days. In the end, the lives of these last people became unbearable, the situation became fatal. No one would sit with them, talk to them, or greet them. Then Allah sent down verses saying that they would accept their repentance.
The Prophet (peace and blessings of Allaah be upon him) severed ties with some of his wives for forty days. Hadrat Abdullah bin Umar had severed ties with his son. In the end he died. The reason for this was that he did not follow at all any of the hadiths of the Prophet (peace be upon him) which he narrated from the Prophet (peace be upon him). In that hadith, the Prophet (peace be upon him) forbade the girls from going to the mosque.
And the one who has a just right will come to his brother and ask for forgiveness, and it is his duty to forgive him and to refrain from quarreling. It is haraam to reject an apology or an excuse. The Prophet (peace and blessings of Allaah be upon him) warned such a person that on the Day of Resurrection he will not be able to attend the Hawz Kawsar near him