About online relationships, I agree with Tias. I've done them in the past. Talking online via chat or e-mail is fun, but in my experience I found no-one will keep up correspondence unless they are very socially excluded in some way.
In fact I found, when I talked to people online, they had to be extremely socially excluded, otherwise you'll have a one-day wonder.
What about when you meet for real, if you meet for real? You're then having to communicate in a way that's different to how you'd communicate online, with the intuition, and all the non-verbal stuff, and all the face stuff etc.