I have a girlfriend with CF and don't know how to ask about how long she has in this life..
My parents were told that I would probably not live longer than my teens, well, I am 45. There are many aspects to a relationship, all relationships take work, dedication, communication, especially to get through the harder times. But as a couple, it may take an extra measure and building on your friendship to get through. In dealing with CF, it can bring some harder times and discussions of the when/where/what that usually comes more as a senior, but comes quicker because we have to prepare for all of those "what if's".
As a CF adult, you can handle things in two ways: be non-compliant and just live your life, taking what comes or you can be compliant, do all the things that are recommended and find ways to betterment your life. It is important to understand though, that even in following all of the standards of treatment, there may come a point that there is nothing left to do or also, to consider a lung transplant. And that has another entire aspect in itself as to how it affects your lives. As CF patients-We aren't all the same, we all find some things have a better outcome and some things just don't help.
In considering a relationship with someone with CF, as others have mentioned, you have to take what comes... together and NOT spend so much time "researching". There will be good days, better days and some really bad days, some unexpected/uninvited event days too. It is even hard for friends and family members to understand exactly what we have to face and deal with, it is usually the friends that you've had the longest that can even come close to grasping what comes and then may go for awhile and then come right back. Many of my friends have willingly "road this roller-coaster" with me and those that didn't, that is okay too, I have nothing against them.
I'll say that in the area of couples, I've been blessed twice in my life. My first husband, Daniel, 40, (no CF), collapsed on a mtn. bike trail and as I like to say, then opened his eyes in Glory. All of my friends/family had prepared themselves for my passing, not Daniel's. In Daniel's passing, through the devastation I was able to see that the Lord had me here for a purpose! My second blessing is that I am happily married to my wonderful husband, Timothy.
You never know what life will bring, but those harder times can bind us together and give us courage to face whatever may come, whether it is dealing with CF or is something that has nothing at all to do with CF. Being loved and accepted brings with it a sense that we don't deserve it, but, yet are so very grateful that we had the chance, took the chance, didn't miss the opportunity and/or give up on "the dance".