What part of Germany is she from?
From the South: she might be a little reserved and cool in her affection, but when she gets to know you, she will be the sweetest person imaginable.
From Central Germany: she might be a little reserved and cool in her affection, but when she gets to know you she will be nice and somewhat reserved.
From the North: she will definitely be cool and reserved, but when she gets to know you, she will be a controlling, heartless woman of iron.
Americans on the other hand:
From the South: Loud, opinionated and friendly.
From the Centre: Not-quite-so-loud, opinionated and closed.
From the North: Loud, thoughful, and closed.