My girlfriend yells out of anger. Is that common with most women?

ALL women are bitches and ALL men are . That is just how it is. It is the degree to which they are that matters.....that is really ALL that matters. Your friend sounds a bit on the high side. In other words....she would be VERY hard to live with....is that what you want? Because it won't change. Maybe minutely but not enough to matter. If you don't like it now....hit the road. NOW.