IMHO I think that both of the options you gave are the same thing. Having a j/o buddy or any other interaction of a sexual nature without your partners knowledge and approval is cheating. Thus having a c2c wank is cheating, as having a j/o bud ic cheating, as having hot tawdry sex is cheating. It is just a different way of cheating. The better question here is on the morality and context of "cheating".