There's an old song that says "Love and marriage go together like a horse and carriage…You can't have one without the other." [Baby Boomers can sing the alternate lyrics, thanks to Campbell's advertising: "Soup and sandwich…"]
Alas, this sentiment is as dated as the horse-and-carriage reference. You most certainly can have one without the other, and so it is with what I call one-sided words—they imply an opposite that does not exist. These are a source of a lot of fun for those of us who like that sort of thing.
Most of the one-sided words I can grab off the top of my head begin with "dis." While you can be either disheartened or heartened you really cannot be either dishevelled or shevelled (hevelled?). You can disburse, but not burse, just as you can reimburse when necessary, but not imburse in the first place.
If I can be disgusted (and, believe me, I can), why can I not be gusted? If you can dismantle a structure, why can you not mantle it? Or remantle it? If I can be dismayed, can you be mayed?
The master of funny writing, P.G. Wodehouse, must have wondered the same thing when he used a one-sided word for comic effect. "I could see that, if not actually disgruntled, he was far from being gruntled."
One can imagine serious writers and critics frowning as they look on such questions with disdain. That's why they are serious, also known as humorless. I, on the other side, look with considerable dain on the situation. What are such language quirks for if not to provide a bit of fun? I find that I am quite gruntled.