SUBREDDIT: r/relationships
TITLE: My girlfriend [22F] called me [25M] out on the fact that I 'never get angry'. Advice?
POST: So my girlfriend and I were having a long discussion on our relationship, and eventually we moved on to stuff that bothered us about each other, and one thing she said that its sort of off putting that I never really get angry. I asked if she meant, well, does it seem like I don't care, or...? And she meant 'No, I know that you care, whether we get into disagreements or not, but you never get angry, and I do, openly, and I think that's sort of weird!'

I don't know what to think. Yes, it's true that she's moodier than I am and she's open and vocal about things that anger  her, but I guess I'm...not? I'm honest about things that bother me and yeah, we do have disagreements and it's definitely NOT a relationship where she's stepping on me (or vice versa), but I suppose it's true that I rarely ever get outright angry. 

The way I view problems is 1. Can you solve them? If so, solve them. 2. Can't solve the problem? You're an adult, deal with it. Getting angry at a problem you can either solve or not solve doesn't accomplish anything and the problem is still there. I feel if I get openly angry, I'm losing control. Note that I don't think this makes me a 'better person' or w/e. I'm still generally no less or more of a regular ass human being like everyone else.

I dunno, I'm definitely not robotic or stoic, I laugh, crack jokes, am social, the nine, I'm a normal guy! But I pretty much NEVER get openly angry. I know its a natural emotion, but I myself never really saw the point in it to express outwardly myself. Is my girlfriend right to feel the way she does?
TL;DR: 
girlfriend is sort of concerned that I don't express anger. I'm a naturally calm guy to begin with and I was raised to view that getting outwardly angry is generally childlike and doesn't solve problems. Thoughts?