I know heaps of people who have met someone over the internet, and believed they have fallen in love with them.
I was once a member of a car forum (ages ago) and I met someone on there and we talked online. I sort of fell into an infatuation with him even though we had never met. We ended up meeting (he was giving me a seat for my car) and I did it safely, like letting people know where I was, what I was doing and meeting in a public place (I was 17).
We ended up getting along really well and even though we lived a few 100kms apart we dated for a few months, we'd meet every other weekend. In the end he moved to where I was living. It didn't work out in the end - he was too needy and unmotivated. I hate people who have no drive or dreams or passions, or people who feel sorry for themselves and refuse to take responsibility for the crap in their lives. Or people who don't take risks. Just thinking about this guy really annoys me - he was so weak.
I don't think its possible to love someone without ever meeting them. I believe you can love the idea of them - but the same way you love cake, or your car. The idea and the reality of someone is often very different but it can take a while to realise that.