We can’t win. If we write what we know, people roll their eyes and tell us we’re inserting Mary Sues. If we write about characters that aren’t at all like us, people suggest we’re acting out our fantasies through our characters. Yes, our experiences and perspectives affect our characters. But most of us are not incapable of realistically portraying characters who think and believe differently.
I have kind of written one story about an asexual person, but I’m not sure if she’s aromantic. She seemed pretty adamant about not dating until she was about eighteen, and then her relationship with a boy she lived with became not really romantic but definitely partnership-ish, and she gets jealous when he spends too much time with other people, but I think we all do that.