What is the empty nest syndrome?
The analogy is from birds, so when the chicks grow old enough and leave the nest (family home), the parent (usually the mother) feels lonely, sad and useless, because she was used to the chicks needing her to feed and survive. I think it doe happen in people – it is bound to when you have been responsible for someone since they were a baby and they go off into the big world on their own. You might even resent them, or wish they were small again.
