Something that annoys me:

Reading a fairly decent, though not spectacular, six book series and never learning the main love interest's first name.

I mean, at one point in book 3 or 4, when said love interest is looking for information on his dead sister, the lead character realizes that she doesn't know his first name.  But she does not do what any normal person would and just ask "What is your name?"

It just bugs me, you know?