Didn't Washington at one time consider himself to be a “good Englishman” and actually fight for the British - before he fought against the British?
There was none of this having to go with one's people even though one didn't agree with them.
Also, taxation without representation was a big issue in the Revolution.
The Confederates had been represented (and over-represented) in Congress and the rest of the government, so it was a lot harder to rely on the right of revolution on the part of the unrepresented.
Washington also believed loyalty to country trumped loyalty to states. See his Farewell Address.