Frath is an emotion.
Generally, you may feel frath when you want to do something, but can't because of the presence of another person--whether because of a drive to be polite, to avoid censure, or because the other person is in a superior position, has other plans, or whatever.
One of the principal components of this emotion is wanting the other person to go away. When you can't tell them to do so, this can lead to an infinite loop of frath. This is a bad thing.
This happens to me a lot. I gave it a name, because names have power.
Frath is a little bit like frustration, a little bit like ineffectiveness, a little bit like anger, and a little bit like independence.