These people believe that if they do not even know the real name of their cybermate—and never actually see them—their affair cannot be regarded as from a moral point of view; it's no different from reading a novel or other form of entertainment.
In other words, a way to play out fantasies in a safe environment.
The private nature of online affairs may make them less painful for the betrayed partner as well.
Moreover, when online affairs are revealed to the significant other, which is done more often than when offline circumstances are involved, it could be considered as something less than cheating.
To my surprise, I found out that she likes to take lots of semi-naked shots, and between one of them she took a shot of her Face time wearing her bra and her facial expression was of that of a very aroused person.
My problem with this was that the guy she was face timing it's somebody that lives about 30 minutes away, and they actually met directly before in the past, as she told me. (2) When you wrote this, you were only dating 5 months.
In such situations, cybersex may even be advisable—but still regarded as cheating.