How can you "cheat" over the internet????
I hope I'm not being misunderstood, but I'm not advocating "net police", or even saying that being on a forum like this is cheating. I'm specifically talking about married people meeting people of the opposite sex on-line, and that it's bad and wrong. That's all.
I know of one sports specific discussion group that has, in the last 8 years, had one girl leave her husband and son to move across the country to be near another member of the group even tho she knew he was living with someone and not interested. After living there for a month or so and realizing that he meant what he said, she committed suicide. A few years later, another couple left their respective spouses and moved in together and later married. All of this from innocent internet chat/discussion.
I think you have to be aware of the temptations on the internet the same as you would anywhere else. The fantasy of anonymity can be dangerous and it could be easy to cross the line.
As far as "cheating" on the internet, I am assuming you have never heard of "net sex". To me, there isn't much difference between that and regular person to person adultry.