oh LilliBeth - you did get the memo that we were all just full our selves and fun didn't you??? lol - Let's see:
If the heat was too low the final product will be too soft
If you stir at the wrong time the final product will be too soft
I know there are other reasons but here is a recipe with what to do with failed fudge:
2 cups Failed fudge, see notes
1/2 cup All-purpose flour
1/2 cup Milk
Mix egg, milk, and flour together until mixture is smooth, then stir into fudge mixture. Bake in buttered 8x8-inch pan in preheated 325F oven for 40 to 45 minutes. A cake tester inserted around the edge should come out clean; center will obviously still be soft. Place on rack to cool.
NOTE - Good use of failed fudge: fudge that is too hard, too soft, too runny, too sugary, too chewy, etc. Proportions are as follows: for every 2 cups (roughly 1 pound yield) of any failed fudge that is not runny, you'll need 1 egg, 1/2 cup all-purpose flour, and 1/2 cup milk. If fudge is soupy, halve the milk (to 1/4 cup). If fudge is as thin as bouillon, eliminate the milk.
"Count yourself...you ain't so many" - quote from Buck's Daddy