I have a girlfriend with CF and don't know how to ask about how long she has in this life..
I have to admit I was once in your shoes when I first started dating my fiance who has CF. although he was upfront with me about a lot of things, I still did a lot of research on my own, for verification I guess. Everyone is right about the internet. I scared myself silly reading some of data. They are out of date and tend to use worse case scenerios. I did feel a sense of relief once I started finding people with CF who are in their 50's, 60's and 70's. While I know that is not a guarantee, which even those of us without CF have no guarantee on our time here on earth, it gave me hope knowing that having CF doesn't necessarily mean you have a shortened life expectancy. Because CF is different for everyone, I would suggest talking to her, her family and going to her appointments with her.
My fiance is 30, great lung functions (better than mine actually), and spends all of his free time at the beach surfing (again...better than me) haha. His parents were also told he probably wouldn't live to be 6 or 7. So, I don't really think doctors can give a life expectancy...