I once saw a problem, iron ions(II) titrated with potassium dichromate to produce Fe(II) and Cr(III). If I am to write the net ionic equation of this reaction, I got to make potassium dichromate on the right into dichromate ion since potassium is a spectator.  

I got very confused over here. Why should you see potassium as a spectator if K(II) will be balanced as 2K on the right.