Whereas people having online affairs tend to understate their problematic nature, their offline partners typically do not see difference between online and offline affairs: A lack of direct physical contact and face-to-face meetings does not diminish the sense of a violation of their vow of exclusivity.
Online sexual activity can involve various activities, such as viewing explicitly sexual materials, participating in an exchange of ideas about sex, exchanging sexual messages, and online interactions with at least one other person with the intention of becoming sexually aroused.
In his stimulating paper, "Chatting Is Not Cheating," John Portmann defends online lust and characterizes about sex; he maintains that such talking is more similar to flirting than to having a sexual affair.
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.
Generally, online affairs are easier to perform and put the agent in a less vulnerable position, as the chances of getting caught or being hurt in other ways are considerably reduced.