Help

My fiancee is American citizen working for a "service to the military" company here in Germany. He has a case of, I don't know if discrimination applies, but sure of unfair competition with this company, as by jealousy he was downgraded by his boss from a manager's position to warehouse worker. We are trying hard to find a lawyer to represent us but all of them wish us good luck, say that he has a case but they are unable to represent him.
How can that be and are there no lawyers who could handle that? The firm is American and he is also, so its a pure domestic issue, nothing to do with German law.