Alice was put on a mental hospital.. so she might have been crazy (or considered crazy at least) u could say that they're soul mates (just like Emmet and Rose and Carlisle and Esme :)... but it was Alice that had seen them together in one of her visions and she sat in a diner(I think... don't really remember) and just waited for him to show up:) and he did heh:D
Alice was held in a mental asylum because of her ability to have visions. There she was the favorite of a vampire who worked in the building. James, a hunter vampire, took the challenge of hunting her simply because another vampire desired her. Once it was clear to him that James was after her, he, the vampire who worked in the asylum, freed Alice and changed her before James could kill her. James killed the other vampire instead. She had no memory of these events and was left to find her own way.
At some point she saw Jasper in a vision. He was searching for someone and Alice provided him with what he was looking for. They found each other in 1948 and by 1950 they had found Carlisle with more help from her visions.
the reason why she doesn't remember anything was that she was locked in asylum for most of her human life.. she lived in the darkness and that is the only thing she remembers.. her vision helped her find Jasper, and she recognized him, not Jasper her..