It's all a gray area, every person and each relationship are different, so it depends on their view of the situation. I think the various lines that can be drawn differentiate between roleplaying, perhaps intensity or individualization of the roleplay to suit personal tastes, or cybering as yourself. No doubt when strong emotions are involved things get much more complicated. If someone's partner wants to watch tv all the time and puts off sex, are they cheating with the tv? I agree everything would be a symptom of an underlying problem in the irl relationship, and I think cheating online is different than cheating irl.