I'm not sure what you mean.
I disagree, at least when you apply the word "always" here. Americans are mainly (not all) comprised of descendants of Europeans who wanted to leave Europe, sometimes desperately so. Our political beginnings are largely based on that idea. In the beginning, Americans wanted to stay out of European affairs and be left alone. Whatever wars we fought against any European power was strictly confined to territories outside of Europe. Such as the Spanish-American War, when we took several Spanish territories (including the Philippines), but we never attacked or invaded the Spanish homeland.
I think it was largely due to our annexation of the Philippines which put us on the playing field in East Asia, which led to our shared interest and cooperation with other Western powers in regards to China. We saw ourselves as "equal partners" with Europe at that point, yet still geographically separated. Even at that point, I can't see any evidence to indicate any desire on Americans' part to subdue Europe.
Even at the outbreak of WW1, the US and its populace mainly wanted to stay out, although public opinion wasn't uniform on the matter. Still, there didn't appear to be any desire to subdue Europe; the main concern was that, if Germany won the war, they would have control of the resources and industries of the entire continent, which could conceivably threaten the US. Since we had grown accustomed to and flourished with Anglo-French hegemony over the world, we had no real reason to upset the apple cart or interfere with the status quo. The main problem in WW1 was, they couldn't achieve anything better than a protracted stalemate with Germany. The two most powerful empires in the world going up against a resource-poor third power, and they still couldn't cut the mustard.
That was the moment that the world realized that the Emperor wasn't wearing clothes. The illusions and myths which had governed the world up until that point had been shattered.
That can't be said to be America's fault. The Europeans were in control of their shared destiny, and they made their own bed. The US may have taken advantage of the situation, but the government propaganda and most public perceptions within America is not that of a colonial master, but more that of a protector. The standard refrain throughout the Cold War and ever since is that Europe is a major prize which must be protected at all costs. Even now, the whole focus is in the US wanting to protect Europe from the Evil Empire, with the hapless (yet friendly and good-natured) Europeans being led by the paternalistic, courageous, confident, and capable Americans.
Americans look at Europe much in the same way staunch militarists look at peace-loving liberals. A perfect example is in Jack Nicholson's portrayal of Col. Jessep in
A Few Good Men.