My DM has always been one of these people who's moods change at the drop of a hat. She can be fine one minute and in an epic sulk the next, she can't deal with any kind of stress or anything not going her way. These sulks can last anything from a few hours to a few days. We are expected to tolerate this.
Instead of saying "oh I've had a really bad day today because this, this and this has happened" she will jump down people's throats, bite their heads off, huff and puff, sigh slam cupboard doors etc.
I don't think this is an acceptable way to behave and I've started challenging it now. But this often makes Her worse and she looks at you in this really hurt and wounded way like you've really slighted her, she does tend to apolgise for it after now, but didn't before I started challenging her.
AIBU to think this is an unacceptable way to treat your loved ones and she should learn to manage her moods better. They are her problem not mine.