Stalin didn't trust the West either
For a POD, have Stalin die in April 1944, and FDR living till 1948, hopefully longer. Molotov will take control of the USSR, and is a die-hard Stalinist, but is not Stalin, so needs support to rule. FDR sets looser strings to aid, and East Europe is Finladized (spelling?) instead of forcibly communistic. France, Italy, Greece, and Czechoslavakia (spelling?) all have strong, legally elected Communist parties.
Although USA/USSR are anti-imperialist, neither will go to war over it. The key IMHO is to avoid the Cold War, ironically, as that means both sides see the world as a zero sum game.
Another POD might be Malenkov/Beria attempt detente in 1953, but I need a nap... I just keep thinking of Watchmen for the POD...