Is it possible to be "dating" someone you've never met in real life?

I’ve been watching a lot of Catfish lately. The show was created by a guy who “fell in love” with a woman online who turned out to be someone completely different when he tracked her down. His show helps people meet people they have met online. Sometimes they are who they say they are and sometimes they are not. The thing is that most of these people say they are dating this person. How on earth can someone say they are dating or are exclusive with someone they have never even met in real life? I just don’t get it and I am wondering what The Collective thinks.