Is it permissible for a woman to leave her fiancé, to whom she is religiously married without official documentation, and who abandoned her and did not complete the marriage, without resorting to the courts or hearing the word of divorce from him?

Since the legitimate marriage contract has been concluded between you, it is not permissible for you to leave him except by divorce or by resorting to the court to grant you a divorce due to harm. It is not permissible for you to leave him and marry someone else because you are still under his marital bond. The lack of documentation of the contract is not a justification, as documentation is not one of the pillars of the contract; rather, it is for safeguarding rights. The contract is valid without it if it fulfills its conditions. If the marriage took place without a guardian, it is invalid according to the more preponderant opinion, but it still requires a divorce or annulment.