Emotional cheating (on that level, cam stuff, at least) is the same as sexual cheating.
Are the cam girls/guys cheating then by talking to their clients?
Like others have said, there's no general rule here, it's up to each couple to decide where the boundaries are. I dated a girl for a while that was a cam girl. She told me up front about it on our first date and she asked if it was something I was okay with. I was cool with it, it didn't bother me at all really. Although it wasn't a serious relationship, but it's not like I would have been okay with her physically being with someone else. I also wouldn't have been okay if she was the one paying to have cyber sex. But since she was the one making money, I didn't think it was bad.
Just curious, would you be ok with dating a prostitute (like the ones who work in Nevada)?