Honestly that is a hard one. The only logical thing I can think of is that Germany doesn't take Alsace-Lorraine after the Franco-Prussian war. Instead it takes some colonies and a large indemnity after the war and makes active overtures to her after the war to smooth over relations. There will be some bad blood for a while no doubt, but not as ugly as OTL. Revanche wouldn't exist or not at least as we know it. Perhaps Bismarck is successful in renewing the deal with Russia, keeping France from having a large ally and they realize working with Germany is better?
Honestly, it would probably take the Fashoda turning hot and Germany coming to France's aid, seeing her as an ally against Britain, her new enemy. Without Alsace-Lorraine bogging down reconciliation, perhaps France and Germany see the British empire as a target for expansion, working with Russia at the same time to press in on Central Asia. It is far fetched but not impossible, though I can't see how Britain would not strive its hardest to prevent this nightmare scenario from happening.