When I am mad, usually it has nothing to do with you. When I'm feeling bad, it's not possible for me to deal with "normal everyday frustrations" that I usually deal with (though they overwhelm me by evening). You might think they are no big deal, but I assure you, its a big deal to me. My brain is already trying to deal with something, you have no idea.
I deal by moving inside my own head. Just let me be. Just let me hide. I'll be present and do what I need to do but I don't want or need your interference. It's very uncomfortable for me to feel like this but if I come out for a moment, I'll just get overwhelmed by something little, then it's likely I WILL be upset at you, for no real reason.
I'm just overwhelmed. Let me be.
Put I this way, I only have enough strength to deal with one emotional thing at a time. If I'm emotional, upset, angry... its just better to let me be. I usually don't really want to talk about it. I usually don't want help dealing with it. I'll let you know when I DO need help, if you let me know you are open to that. Eventually, or sometimes, I do need to talk about things. But for the most part, give me some space. I won't hear you, I'm inside my own head. Let me be there. I'm safe there.