It’s apparently a rare french form of [name]Alexandra[/name].
What are your thoughts on it?
The -ie ending gives it a bit of a nicknamish feel, but I’ve actually never found a form of [name]Alexandra[/name] that I’ve disliked, and this one is no exception. 
I like it a lot, actually! I’m not a fan of most [name]Alex[/name]- names on girls, but I have had a thing for [name]Alexandrie[/name] for a while. It’s novel and interesting. I remember seeing the combo [name]Sophia[/name] [name]Alexandrie[/name] months (if not years) ago and thinking it was utterly perfect. I don’t think I would use any [name]Alex[/name]- name for a FN, but I seem to love them in the MN spot. I think with a soft-and-sweet FN (like [name]Claire[/name]/[name]Clara[/name], [name]Sophie[/name], or [name]Lena[/name]), [name]Alexandrie[/name] would be a cool MN.
Oh you raise a good point! [name]Alexandrie[/name] would be gorgeous as a middle name! It’s now on my list.
I like the sound of [name]Alexandrine[/name] a little better. [name]Alexandrie[/name] just sounds incomplete to me.