Honestly, this is the first time I've heard of this actually happening to someone. I'm sure it has happened before but never to me or anyone I've known. Tbh, it feels like she didn't like your stutter (or at least the way you portrayed it, like you mentioned being very uncomfortable with it) and made the excuse of being introverted. Idk what to say except it seems like you dodged a bullet. And it's good that she came out early with it. I'm sure it hurt your confidence and self esteem but take it for what it is. Idk how german culture is towards stuttering (I've never had a problem with Germans regarding my stutter) but it seems like she's an oddball. Like I said, there's plenty of reasons girls don't like me (I can be a real dickhead lol) but my stutter was never one of them, as far as I can tell.