I tried to mediate two co-workers with this same issue today- one explodes when she is frustrated, and the other hasn't been expressing his feelings about that and has been avoiding her. Today I tried to get them to hear each other, and that did not happen. He is avoiding her because she blows up. She is upset by that, but acts like she doesn't know why. He is barely talking to her, and leaves her out of important conversations, but couldn't acknowledge that this makes her feel isolated at work. She glosses over the impact of her yelling. I might as well have been talking to cats. "You- don't yell! And you- don't freeze her out! GROW UP, YOU STUPID, DUMB CATS!" I spent a couple of hours on this on my day off, which he asked me to do. Neither of them thanked me.