I saw a zombie movie once that I haven't been able to find.
The story centered around a girl who gets infected, and her boyfriend (or guy friend) tries hard to keep her sane and stop her from feeding. The transition process was hard to notice at first; I think she could still talk and everything, and she still clung to the guy. Early zombie-hood in this movie involved the inability to feel pain, and at one point the girl pushes large nails through her hands and uses them as weapons.
It might have been part of a series.