Booksandtrees:
I am just putting it out there right now that Injeolmi the chat friend is Yi Jin given the 6 degrees of separation narrative arc in k dramas.
I'm not so sure if it's him. Then he'd be lying to Na Hee Do that he didn't know her. What about the Go Yu Rim issue, Hee Do wrote to her chat friend everything about it, if Yi Jin knew about it, wouldn't he explain her behavior or try to excuse her? Unless he don't want to get involved in their affairs. But when Hee Do said to him that he is cold and inaccessible as Go Yu Rim, he seemed surprised? Or, you may be right, usually it is like that in dramaland :)