Wow DQN and /b/ moved in here pretty fast... And >>21 needs to learn the point of sage.
In any case, to me, it doesn't seem like online relationship could really work out. For companionship, yes, they could last quite a long time of chatting and so forth, but I'd never expect anything like marriage to come of it. I've talked to a close friend for about 1 year now without any real life contact but rather online. We share a common interest, FFXI.
I see people in-game declaring their love for one another (and through in-game marriages), but it kinda reminds me of "grade school romance". "<3 Seipher 4eva!" and whatnot.