ABANDONED. Obscure science fiction book, girl wakes up in bed, goes out walking around a city. She can't remember who she is or where she came from. Finds man, she is his other half.

[Brita]

I can't remember a lot about the book.
What I remember is:
A girl wakes up in bed, goes out walking around a city. She can't remember who she is or where she came from.
If I am remembering the book correctly she ends up finding a man who had talked to her and even written about her. I think they realize that she is his other half. And if I recall she gets information from the internet without asking and she remembers walking and running around the internet with her sister.
This is really bothering me and I would really like help in finding the title and the author.
Thank you.

[Tab]

How many years ago did you read this? Was it for children, teens, or adults?

Remember anything about the cover?

[Lobstergirl, au gratin]

Brita, are you still looking for this or did you find it?

[Lobstergirl, au gratin]

No response in 2+ years. Moving to Abandoned.