Sorry to hear about your experiences with this particular routing.
But, it has been mentioned many times over the past three years both in the magazine and on this Forum, that all Lufthansa non-hub flights would/have been switched to German Wings which in turn will be branded EuroWings from next month.
We reported on this development three years ago.
And last April we broke the news that the German Wings name would be retired later this year.
It means that Lufthansa would rather passengers hub through Frankfurt or Munich rather than take those very few long distance flights it continues to operate from regional airports.
In fact, according to lufthansa.com all the Manchester-Chicago connections that I can see are for routings via either Frankfurt or Munich.
I do hope everything works out for you.