expostulate about (someone or something)
To engage in a passionate discussion or argument about someone or something. Oh boy, steer clear of Uncle Ed if he's expostulating about politics again.
expostulate about someone or something
and expostulate on someone or somethingto comment or argue intensely about someone or something. He always seems to be expostulating on something. Why can't he simply say "Yes" or "No"? Sam is expostulating on Bill's many shortcomings again.