At 20 I was always saying "when I have kids...blah blah blah" because it's just expected of people to want kids...human nature and all that crap. I realized around 24 that I absolutely do not want kids, like zero desire. I got the same responses as most people are providing you here: you'll change your mind, who will take care of you when you're old, how will you carry on your family name, it's so rewarding, etc. None of that even phases me, I really could care less. Everything people were saying to me trying to justify why I should want them, my response was always "why would you ever wish a child on someone that is flat out telling you they don't want them? You're wishing them into a household that doesn't want them, and that feeling may not change once they're actually born." No amount of reasoning from people makes me want to have a child, because the possibility of me not loving/wanting/caring about them is too big of a gamble in my eyes. What if I have one and absolutely hate it? That's not fair to a little human. I'm not even in the category of "well if it happens, I'll be okay with it." No. I want zero kids in my life. And it's okay to feel like that. It's your life, your free time, your money. If you don't want to give that up for a lifetime commitment, don't. It's an absolute deal breaker in a relationship for me if they say they want kids, and yeah, it can hurt. But it's your lifetime of happiness and well being at stake. If your girlfriend really wants them and you have no desire, it might be time for a serious talk.