Well technically you're in a relationship as soon as you and this other person are relating to one another. I suppose the problem is defining said relationship, right?
What kind of relationship is it? Is it dating? Is it friendship with interest in maybe one day being romantic? Is it being romantically interested without commitment? Is it a long term interview until they pass the "marriage material test"?
In terms of online relationships--having been in a few before--I have done it both ways. My first boyfriend and I met online and talked on there and on the phone until we met.
Then we decided to go out. He was pretty local to me so this was no problem. But I didn't date him until we had meshed together in person. the desire was there, but the commitment came later.
For
long distance internet dating... that's a tough one. Yes, I think you can be in a romantic relationship with someone you have not met face-to-face, but it's not recommended by me. It's much more of a gamble. No matter how you get to know someone online, things are always different in person. Having had two long term relationships that started just like that, I'm only speaking from experience.
I'd much rather meet, if at all possible, before making the decision to be in a marriage-minded relationship with them (and the way I date at this stage of life is always marriage-minded). I want to see how we relate in a common space and in real life situations instead of in the intense bubble created by online/phone relationships. They are wonderful, but not naturally made. They're like genetically enhanced vegetables--yummy and delicious, but not grown the same ways.
so can you be? Sure, I think so. I have been before. Is this right for everyone? most likely no.