Whether I was sitting on the couch or sitting on the bed, as soon as I get up, my little dog starts digging ferociously in that spot. I understood why she would lay there (because when i get back she gets lovin). But the digging/scratching my spot is weird.
While this tendency seems weird to humans, dogs have exhibited digging behaviors long before they were domesticated for human companionship. If your dog is a terrier breed, she is especially susceptible to dig, for they were initially bred to dig holes and to chase rats out of said holes. If your dog isn't a terrier breed, she is probably doing it to allow for maximum possible comfort. Another likely reason is to mark her territory, particularly if you were just sitting there. It is probably a sign of her affection for you and her attempt to claim you in case another dog should come by. Lastly, she could do it to keep herself entertained. Digging is a behavior trait encoded in canine DNA meaning they feel the need to dig and it satisfies them to do so. If your pup's digging becomes an issue, you can try using seat protectors or covering your bed in an uncomfortable material (tin foil, carpeting, etc.) when you get up to discourage said behavior.
It's warm, it has your scent, which is appealing and comforting.
The digging/scratching behavior has natural instinct roots in creating a safe nest before lowering their bottom to the ground, this also spreads their scent from their paw pads.