Welcome! So sorry you're going through this awkward interaction. I can only reiterate what the others have said. Only you are allowed to define yourself. And you don't HAVE to define yourself as anything if you don't want to. If identifying as aromantic makes you feel better in your skin today, then embrace it. And who knows, maybe you will find someone to share a romantic relationship with some day. And if you do, you can decide to change your definition to whatever fits you best. But if you don't, if you don't even care to look for that option, if the mere mention of it gives you the squirms, you are completely entitled to take whatever direction suits you best. You do you, live your best life, and don't think you owe anybody else an explanation for how you feel or who you are.