Is the son sinful for obeying his mother and leaving the house after his father expelled him, preferring the maid over his mother?

Our advice is that you approach your father and apologize to him in the best manner and at the appropriate time. If he does not accept, then let someone whose word he trusts mediate between you. Show your father love, obedience, and kindness so that he knows of your regret. And handle the matters of your future home wisely by consulting with your father and discussing matters calmly with the intention of reform and overlooking what the Sharia does not prevent from being overlooked.