Question: do mother dogs get sad when their puppies get taken away?
Answer: If all the pups disappeared at the same time she may be worried about what happened. (But I've never found homes for all the pups in one day.) The newly adopted puppies are more likely to be lonely. But will probably miss it's litter-mates as much, if not more than it's mother (as long as it is 7 or 8 weeks old).