Hey Mary - Rose
It really depends on your situation. How long you have been with your patner, or when you want to have children etc. Before you bring up the issue you have to ask yourself is it time, are you planning on having children with your partner within the next year or so. If you're not there's no real need to get tested. I'm 21 and have been with my love for 4 years. He will be getting tested summer '05 for the cf carrier gene as we are planning on starting a family soon. The issue of getting tested is a delicate issue though as the person who is getting tested may feel a lot of pressure as the decision on having your own children may rest entierly on the outcome of the test.
It is important to discuss your options with regards to the outcome of the test, ie if the test is posetive will you adopt or have your own children regardless. You should do this before the test. This may clear up some issues and you can discus with your patner his views on having a baby with CF or adopting.
I hope that helped a bit, sure I'm only a young lass myself so I'm just going on my own(limited!!)experince!!