My girlfriend gets upset when we play games, but she never talks to me about it.

My girlfriend (20F) sometimes seems to get easily irritated, especially a couple of weeks after her period ends. We enjoy playing FPS games together, but even after a winning streak, she often ends up feeling moody or frustrated. Sometimes, she'll go on her phone and suggest taking a break to grab some food, which I don't mind since I have other things to do. However, after that, she sometimes refuses to turn on her camera (we're in a long-distance relationship and FaceTime while playing) and talks to me in a sad or annoyed tone. When I ask what's wrong, I usually get responses like "Nothing" or "I'm fine." This leaves me uncertain about whether I've upset her during the game or if she's just hangry. I tend to overthink things due to anxiety and past experiences, which makes this situation even harder for me. I'm just curious whether it's common for women to experience sudden emotional shifts or if being hangry is a real thing. Any advice would be appreciated—thanks!