We are child-free by choice. I've known since I was a teen that I did not, ever, want children. I don't particularly enjoy children. I find them cute, but from a distance.
I think some people don't know how to react to someone who doesn't want children, so they seem to go on the defensive. I just ignore them.
I think some people find it weird or off-putting when someone doesn't act in a way that is in line with most of society. I just ignore them.
I think some people feel the need to have us all fit one mold and tell me that I will want them eventually. Well, I'm 45, so no. I just ignore them.
Finally some people feel the need to pity us. I just ignore them too.
I do think people know no boundaries in the questions they ask. Even Uber drivers will ask just in conversation, oh do you have a family? And when I say we have no children, they go straight to "why" - not realizing it's really none of their business. I just say we didn't want any and leave it at that.
I find when people do have strong reactions to it, it's mostly men, don't know why.
People ask all the time if we have kids, I'm used to it. I say "yes, we have two cats" and ask if they want to see pictures. (we've also been together 23 years and aren't married - we really get the questions then!)