What would u do if the person u were w/told u that they didn't want to have kids?

What would u do if the person u were w/told u that they didn't want to have kids? We have been together for 2 years & are totally in love. There has been talk recently of marriage. I would never doubt that we would be happy together for the rest of our lives. My only concern is how I might feel 5-10 years from now. It is scary! I can't imagine my life w/o him but sometimes I am scared about the future. If I just walk away w/my heart full of love & try to find love again w/a willing partner than it is like trading a certainty for a possibility & in the end I still might not be happy. On the otherhand if I stay then although the issue could be suppressed for the time being it would one day come back up & bite us & then we would have to deal w/it & in the end I still might not be happy. I'm in my twenties so I don't know how I might feel later on he is a little older so I don't see him changing? So anyone out there experienced a similar scenario & how did it turn out or any advice.