Why is "happy" the only emotion that can be "un"?

There is no such thing as being “unsad” or “unangry.” So how come “unhappy” is a word?

What about Unexcited or unfazed ?

… unafraid, unashamed…

Well this is uncomfortable…

Uncaring, unfeeling.

They may have been unprepared

On the other hand, have you ever heard of anybody being derwhelmed?

From etymonline.com

How come you never hear about gruntled employees? Only the disgruntled ones?

I think the concept of polar opposites might be what you’re thinking of. We can (if we want to be a bit silly about it) give a happiness rating from minus 100 up to plus 100. But I don’t automatically think of anger as even having a polar opposite. (Does it have one after all, and I’m just missing it?) Anyway, I can only rate anger from zero to plus 100 - the negative values don’t make sense to me.

Now… ARE there really polar opposite emotions that we name “happy” and “unhappy”? Or is that just a convenient way of talking, but with no factual basis in the study of emotion? I don’t know.

https://pdfs.semanticscholar.org/590a/c3fc3befa20d527a60e5be1c40243bf0f576.pdf

I hope my answer doesn’t leave you unsatisfied.

There’s the dead and the undead.

There’s the enthusiastic and the unenthusiastic.

I, for one, am unabashed.

I’m undeserving

I’m combobulated

But are you hinged?

Is this an unserious question?

I’m unsure.