Consider this reaction: Just as casual sex is not necessarily inherently harmful, neither are online affairs.
But they may be so when participants are also involved in another primary offline relationship, because of the harm imposed on those partners.
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.