Is it permissible for a father to refuse his engaged daughter's marriage on the pretext of completing her studies, while she fears falling into the forbidden due to the prolonged engagement period, and his refusal even to perform the marriage contract without consummation?

You must repent for what has occurred, and what your father did by preventing the marriage is not permissible. A father must marry off his daughter if a suitable suitor comes to her, otherwise, widespread corruption will occur, as the Prophet, peace and blessings be upon him, informed: "If someone whose religion and character you approve comes to you seeking marriage, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." Try to convince your father through someone who has influence over him, and frankly tell him of your fear of tribulation, and promise him that you will complete your studies. If your father insists on preventing your marriage, he is an oppressor, and his guardianship falls, transferring to the judge. Our advice to the girl is to fear Allah and curb the reins of desire.