IIRC, it was during the official celebrations of signing the Franco-German Treaty of Friendship and Cooperation in 1963 that De Gaulle, after asked by Kissinger how France would maintain its position in relation with Germany once it (inevitably) exceeds France in economic potential, his anwser would be "par la guerre" ("through war"). Franco-German friendship might be something we talk about, and view the period of time after WW2 as this being the case in retrospect, but at those times in the past it often wasn't the case. France was particularly not too comfortable with those parts of "western unity and integration" that breached its national interest. The crisis of the "empty seat" comes to mind, but Franco-German relations being cold, either due to the "small reunification" with Saarland, "large unification" with DDR, formation of the Bundeswehr and other situations could have resulted in the post-war period being viewed as "traditional Franco-German rivalry" rather than "friendship".
Anything ending the cold war eariler could do the trick really, once the USSR is gone, the lack of a common foe would inevitably shake the "Franco-German motor" - how fragile it is we saw during the last French elections and the time before that with different ideas on how to stop the Euro crisis. Maybe Beria takes power after Stalin and goes through with the "Stalin note" proposal fairly. Or the Suez Crisis goes awry leading to NATO structures being significantly loosened, France sticking to itself, Germany keeping with the USA. To better anwser the question, one would have to say what constitutes "friendship", and what the lack of it. If France and Germany had more conflicting interests either in Europe or elsewhere, media reported things differently or the two countries not changing their education systems to end the mutual hostility, we could easily see the two entering the XXIth century in the same relations they had pre-1870 or post-WWI.