I'd say we need more context to say anything about this friend. I have friends who are very 'hyperbolic', but seem so honest. It's like they experience things as a child, or for the first time.

I also have friends who do this, where it seems to be a mask they put on. These friends often have rather unpleasant pasts.

It's a bit like the manic pixie dream girl, to use a fascinating stereotype. I have often tried to delve deep, and it's sometimes really hard to discern the 'broken' kind from the truly 'child-like' type.

Broad strokes, I know, and please forgive me. The only point I want to make is that context is everything in this case.