SUBREDDIT: r/relationships
TITLE: Me [18 M/F] with my girlfriend [16 M/F] for a year, getting annoyed by her.
POST: My girlfriend has always been the type to text "DO IT" or "go go go!" whenever I joke about doing something crazy. It was funny, but now I find it annoying because I would like a serious answer. She's also kind of ... slow? I feel that recently, she's been getting lost or suggesting stupid things and I have to say "Bae... I already did that last week. I'm talking about this". She's a big nerd about random things, and now I'm getting annoyed whenever she talks about them. When she makes grand plans about her future, it's annoying because it's such stereotypical "teenage talk" and I thought she knew better than that.

Is this just a relationship thing? Is this just simply the end of the lovey dovey phase? I've felt annoyed at her before, but lately it's starting to really get to me. Maybe it's part of the age gap thing? I don't know.
TL;DR: 
My younger girlfriend seems more annoying lately. I don't know if this is just me getting used to her, or if I simply like her less.