If the Nazis went strictly East in WWII instead of also West, then perhaps the Brits, Americans, French could convince themselves that they didn't need to get involved.
The Wehrmacht beats the Red Army without the Allies, and set themselves up as overlords of Central & Eastern Europe. The military and technical edge the war has given the Germans allows them to face-off with the Anglo-alliance, which belatedly comes to realize the existential threat the Third Reich poses to 'Freedom and Democracy'. Neither side is confident enough to be overtly belligerent, and so the Allies and the Reich settle for uneasy Cold War, skirmishing for dominace through proxies in the Middle East and SE Asia. The expected flashpoints are in the Zargos mountains, where Reich ally Persia meets with British friend Iraq. Oil flows easily from Persia over the Caucasus into the Empire, while the British need to ship tankers around to Suez or even via Cape Town - the Mediterranean is not an entirely safe place for unescorted allied shipping. Albanian and Turkish raiders are freely set loose by their German masters on trade and cargo in the Eastern Med.