SUBREDDIT: r/relationships
TITLE: I [24 M] have a girlfriend [23 F] of one year whose mood changes very frequently. Is that normal? This is my first serious relationship.
POST: I realize it's normal for peoples' moods to change and females' often do so more than males. But I'm wondering if this is more fluctuation than normal. 

Some days she is very happy and smiley and continually tells me how much she loves me. But sometimes the very next day she'll act uninterested and like she's doing me a favor to talk to me. Nothing at work changes, she's not on her period. It's just like BAM mood change. Is this a typical part of being with someone day to day? Or should I be concerned?
TL;DR: 
Her temperament and attitude toward me go up and down day to day and I'm wondering what a "normal" amount of mood fluctuation is.