It is deeply irritating to me as well, and I know exactly why. The "unity" they desire is the entire country doing as the left desires; any resistance by we who see this and understand what it means for what remains of our liberty, our national ethos as Americans, is characterized as "gridlock" and "refusing to compromise".
That the right is painted as "refusing to compromise" by the left resonates most keenly with the squishy middle, who have no hard and fast principles as they pride themselves on picking items from Column A and Column B, according to their feelings and little other criteria, and calling it virtuously "independent".
This American is, indeed, fed up, with being called scurrilous names, accused of unconscionable language and behavior and demonized as being unpatriotic for refusing to cede any more sovereignty.
Unity is done and it is the left that has wrought it.