Yes he could be still charged.
That would mean your gf would have to get up on stand(if he doesn't plead guilty) and tell in amazing detail the story of her abuse. And, he could still get off with a slap on the wrist or nothing at all.
That is what stopped me from pressing charges against my former stepbrother.
I watched one of my friends who charged her father go to trial.
The questions they asked her, she had to relive the abuse. Hours of endless questions about the most painful experience in her life.
The ba$tard got off. Found not guilty.
That's one side you and she need to be prepared for if you do get him charged.
Please, please don't get me wrong, I think all molesters should be casterated and tortured. But I don't wish to relive my worst nightmare. *cough* take it into personal hands*cough* I do not condone illegal activities. Take what you think I mean from that statement. Be smart about it.
sidenote: what does your gf want?
Never argue with an idiot, they will drag you down to their level then beat you with stupidity