One of the proposals which German diplomats proposed to France was for a separate peace in the West. Hoping to cut a deal with a left-wing government (something that could have happened given a slightly worse spate of mutinies among the poilus and corresponding lack of interest in the war), Germany proposed to annex Briey-Longwy, Luxembourg, and bits and pieces of Lorraine, as well as eastern Belgium. In return, France was offered the rest of Belgium.
What I'm really curious about is what the short-term and the long-term effects of such a deal being made are.
Where does the British army in Flanders go if France is no longer fighting Germany? What do the Belgians and their king do, if France is going to annex western Belgium, including the tiny strip they occupy?
In the long-term, what happens in French and German-occupied Belgium? What is the effect of the Great War on French national morale?