Actually Tamara, as I see it, the answer would have to be no. (Not to say it's impossible, just too risky to be realistic)
I'd go further, but am a little to self-concious as to how I'd reply the reasons why. I thought of the same thing, when I had a crush on another girl who had CF. At that time, b. cepacia and other hard to beat lung infections were not around, yet. But, basically, to answer the easiest way, it would be difficult for both to take care of each other when they are both sick at the same time.
Hopefully someone else can add more reason to what I've already expressed.
btw, if you go to the "Young People" section and scroll down, someone asked pretty much the same question.