The problem with on-line affairs is that most people involved in them don't think of them as affairs. It's not like they are "cheating" for real. So some people who would never even dream of having an affair find themselves having an online affair. They can be who they want to be, and "do" what ever they want to with out any real risk or consequences. It is not like they are meeting the person at a hotel room or something. There is no real contact so it does not hurt anyone.