This is the most "thought provoking" topic I have seen on the Question List. Good job!
Do I believe in virtual relationships?
Well. . . it is a fun thing to have someone to communicate with when you have nothing better to do. The anonymity allows for more honest disclosure to someone you'll never meet. If anything: They're a good way to kill time.
Also, you're able to project any sort of personality on your virtual friend to "fill in the blanks."
So the answer is: Do I believe? Yes, in a way. However, your real-life relationships are much more important.