Not the fish - the internet phenomenon.

Watched an episode of this reality TV show last night. What I get is it's kind of like 'cheaters' but with people who have been "tricked" by people on social media into believing they are someone but then turn out to be someone completely different.

People actually going as far as stealing pics of someone else and making up an entire new social online identity and then having a relationship with someone for years.

So my question is:
1. How can people carry on relationships with someone they never meet FOR YEARS? - Actually know a guy who carried on a 5yr relationship with a girl he never met. Everytime he would say he was going to fly over to meet her she would make up excuses - crazy ones like: She was in rehab for anger issues, her mother was dying of a rare brain cancer (but then a month later was cured). Everyone would tell him this was clearly not right and he should move on, but he was adiment that it was real. Finally after 5yrs, he realised it wasn't. Not sure what happened, but it ended suddenly.

2. Have you ever had your identity stolen for online catfishing? Knew a girl who had her pics used on a dating website, she confronted the 'girl', turns out it wasn't even a girl who used them.

tl:dr
Been done before?