What is the legitimate Islamic way to deal with a colleague who does not differentiate between personal and professional relationships, harbors resentment, and refuses to approach and reconcile, while adhering to the prohibition of estrangement for more than three nights?

Allah Almighty has enjoined kindness to neighbors and companions. The Quran commands good speech to avoid the devil's corruption among people. It is advised to treat colleagues kindly, seeking Allah's pleasure, and to embody forgiveness and pardon; for forgiveness increases honor, and it is a path to attaining Allah's forgiveness and pardon.