This is the face you have when the words won’t come out, and you have a lot to say. You want to say something important, to someone, and what happens is that your voice vanishes and you can’t even breathe. That feeling of impotence, accompanied by sadness and regret of not saying what you should have.
Nothing comes out, not even a breath and you just stay there, or biting your lips or holding something in your hands, or just staying, yes, just being there. Feeling so disappointed with yourself.