Oh yes you can, I'm a living example of that.
Thas how I met my first GF. Of course we chatted hundreds if not thoudsand of hours before on internet...for like 3-4 months or so. We both admited that we love eachother. We talked a little on the phone but not too much cause my SP.
Anyway, in the last months that we chatted we started sending each other love e-cards and such, even sended real gifts to each other. After we finnaly met, it was like we knew eachother for a lifetime, of course our love grew a little stronger cause of real kisses (not virtual ones we kept sending till then), but I'm saying it is possible to fall in love online.