My g/f gets pretty upset over something probably twice a year, not often. And every time I dunno what to do besides give her a hug, try to agree with her (usually her reasoning for being upset is a rational one), and cuddle with her. Maybe go for a walk to get her mind off things. I'm not a man of many words so trying to talk it out would probably not work well. In most situations what would you do? Just be a listener or try to solve the problem and give input?