If your boyfriend doesn't want a child but you love him? Is it reasonable end a good relationship?

A girl of 25 has been with her 23 year old boyfriend for a year. They're in love. She has been told that she has a medical problem and only has one more year to have a child. They both want to marry but the guy doesn't want children yet. He feels he's too young. So she ends the relationship. Surely if she loved him she would have stayed? What do you think?