Is a mother sinful if she cannot forgive her daughter who wronged her and caused her severe psychological pain, given the mother's fear of God's punishment, and the daughter's desire to return without seeking forgiveness?

Allah has made it obligatory upon a servant to honor their parents and has forbidden their disobedience. It is not permissible for a Muslim to abandon their brother for more than three nights, unless there is an overriding benefit in abandonment, or if harm to religion or worldly matters is feared from communication, in which case abandonment is permissible. If the abandonment is due to a sin committed by the abandoned person, and the abandonment disciplines and deters the abandoned person, then it is permissible, unless a greater harm results from the abandonment. If the reason for the mother abandoning your sister is her abuse and hurtful words, then this abandonment is legitimate, but it is better to intervene to reconcile between them.