What is the ruling of Islamic law on continuing to pay monthly profits from the capital without realizing a profit, and is this considered usury (riba), especially if the only remaining option is a usurious loan to recover the capital?

One of the conditions for the validity of Mudarabah (definition) (profit-sharing partnership) is that the capital is not guaranteed. Therefore, if the capital owner stipulates that the worker bears the loss, or if the worker undertakes to do so, the Mudarabah is فاسدة (invalid/corrupt). In such a case, the capital and its profit belong to the capital owner, and the worker is entitled to a wage equivalent to his services (أجرة مثله). In the event of a loss, the entire loss is borne by the capital owner, and the worker receives a wage equivalent to his services. If there is a condition to guarantee the capital, this leads to Riba (usury/interest). If this condition is not present, the Mudarabah is valid, and the worker is not obligated to return the capital in case of loss without negligence (تفريط). It is not permissible to borrow with Riba to repay the capital under any circumstances.