Absent a common threat, an alliance or "economic partnership" (whatever that means) is probably too much. However, there is no reason why America and Germany could not be very good friends.
There is a very large German-American population. America actually adopted a lot of German educational policies (all the way from kindergarten to university). Germans had a very good reputation in America. What caused eventual American hostility towards Germany was:
1) Prussia/Germany was not illiberal.
2) Kaiser Wilhelm and his policies were seen as dangerous
3) Germany seemed to want to interfere in the Western Hemisphere
4) Stronger cultural ties to France (from Lafayette onwards) and Britain (because of a common language) made the US want to intervene on their behalf.
If Germany became more democratic/liberal that would be a big help. Then if Germany became opposed not to France and Britain, but towards Russia, "the prisonhouse of Nations" then American sympathies could become very pro-German (especially if it was combined with a movement to liberate the homelands of lots of other American immigrants like Poland, Ukraine, and Lithuania).
Let's say things happen differently. The liberal Kaiser Frederick III and his wife Victoria have a long reign in Prussia/Germany that establishes a strong constitutional monarchy. Their heir is not born with a withered arm, and the boy has happy childhood without an inferiority complex. He is more than happy to continue his parent's policies.
At the same time, Germany follows Bismarck's policies of avoiding a colonial empire. Maybe Germany gets a few colonies, but there is no nonsense of trying to expand into other power's territories. Instead, Germany develops its economic interests in Central Europe, the Balkans, and the Middle East.
Germany attempts to conciliate France, keep good will with Britain, and reserves its ire towards autocratic Russia and its Pan-Slavism. Germany plays up the difference between the liberal West and autocratic Russia. In order to blunt appeals of Pan-Slavism, it encourages the nationalism within Russia and takes a strong pro-Polish and other minority policy. Or at least sympathetic towards as much as can be done in peacetime.
Then if a great war breaks out, Germany announces its goals are to liberate Poland, Ukraine, Finland, Baltics, etc. Power politics wise, it is simply to break up and weaken Russia, but it plays very well with America. As the only major European power without a substantial colonial empire (or large ethnic minorities), Germany becomes very popular in America, and the large German-American population combined with large Polish-American, etc. population strengthens ties between the two countries even if the great war struggle includes France (but not Britain) against Germany.
By the 1920s and onwards, there is increasingly partnership between the US and Germany in foreign affairs especially as both countries see benefit in harassing the other great powers for their colonial empires. Both see themselves as a model for potentially independent countries and excellent business opportunities.