I don't want to get into geo or euro politics, hyperpower containment, etc. The problem with France is that it never got over the loss of influence and power. It had to be rescued twice in the past century by the USA from the Germans (we can debate the point whether 1945 was a liberation since, after all, the French collaborated with the Germans from 1940) but still clings to the notion of a great power while having problems projecting power even in its own backyard (see NATO involvement in Kosovo). It cannot or doesn't want to build a decent aircraft carrier on its own (see recent deal with the British) and yet it wants to dictate policy priorities and directions to the USA through UN.
But lets not forget what helped them and the rest of Europe into the mess of impotence coupled with lofty ideas. It was US nuclear umbrella during the Cold War that allowed them to drop their military while boosting social spending. Despite high taxes (remember Mobil 1 and gas prices?) and US military protection they still wasted all the money on pet projects and wasteful social engineering (see "Of Paradise And Power" by Robert Kagan).
And now you have the results. High taxes, low productivity and GDP growth, declining employment coupled with generous retirement (pay as you go) package, etc. All of that amounts to lower standard of living without a chance of ever catching up with the US.
Happy reading.