Because a lot of people haven’t heard of it: amatonormativity describes the way society expects everyone to want a relationship and prioritise romance/starting a family and having kids over other things in their life. Aro or not, you have likely come across this sentiment in your life.
Examples of amatonormativity include: parents who think you owe them grandchildren, co-workers and friends asking why you’re single/not believing it’s by choice, the idea that you’ll “change your mind” about having kids when you “find the one”.
Examples also include: thinking you’ll “find the one” at all, assuming everyone “settles down” with a partner at some point, telling people you don’t have a crush and nobody believes you, the entire concept of soulmates
Additional examples include: “you’ll have to start your own family eventually”, older singles thinking that their lives and accomplishments are worthless because they’ve never been married or had kids (my current roommate). The “You can’t really want to be a single parent!” And “its imposible to date with a kid, just wait until you get married to have one.”