It wasn't ok, but the big deal was less the fact that he cheated on his wife and got some head, but instead LIED ABOUT IT ON THE STAND.

THAT IS THE BIG DIFFERENCE, HE COMMITED PERJURY, THUS HE WAS IMPEACHED.

McCain just came back to his wife who loved him all the years he was gone and stuck by his side, only to dump her because she got into a disfiguring car wreck and didn't look like the barbie she was before he left. So he felt a little guilty and decided to pay for her medical bills for life (probably in exchange for her silence) and found himself a barbie.