I(22m) am considering breaking up with my girlfriend (23f) because she changed her mind about wanting kids. Why is this so hard?

My girlfriend (23f) and I (22m) have been dating for a little over a year and a half. When we first began dating, we brought up the idea of wanting kids later in life, just to make sure we were on the same page, if things ended up lasting. We both agreed on the fact that we would want kids when we get older. Not specifically with each other, but just kids in general. This is something that I am not willing to compromise on, as I know for a fact that I want to father at least two kids later in life.

However, a few weeks ago, my girlfriend casually brought up the fact that she had changed her mind about wanting kids, as she no longer wants them so she can "live her life to the fullest" and things like that. There's nothing wrong with her reasoning in my eyes, but I haven't been able to stop thinking about this conversation. I tried to talk more about it, but she said it was a conversation for another time.

We've had our fair share of troubles, like most (if not all) couples do. However, it's never been anything that we couldn't get past or grow from. But this has just been burning in the back of my mind ever since it was mentioned. I'm typically kind of a pushover when it comes to pleasing people, but having kids, since it's such a significant commitment and decision, is something I won't compromise on.

My love for her hasn't changed after it was brought up, and I feel so ashamed to even consider breaking up when she didn't "technically" do anything wrong. I don't want to break her heart, but at the same time, I don't want to lose the opportunity to have a family later in life.

Any and all advice is appreciated. TIA

TLDR: Gf and I both said we wanted kids when we started dating. Gf changed mind a few weeks ago and doesn't want kids anymore, but I still do.