What do you do?

What do you do when the main of your dreams doesn't want kids? And Everytime you bring up, kids or marriage it's "we need to slow down. We are young" at 25 and 30 you'd think you would be ready to settle down. You would think about 4 years of being together these things would be known by now. What do you do when all you want is a happy life, loving husband, and a little one to hold? But your other doesn't want that. What do you do? Every time it's brought up it is the same thing.