Pandas are solitary animals, they do not live in families like humans. It is natural for the infant of the previous birth season to depart before mating and the next birth can occur. Hua Mei has been eating bamboo and biscuits since last September. The mother's milk declines in nutritional benefit as time passes. Bai Yun has restricted Hua Mei's nursing time for several weeks before we began the weaning process.
Separation has to occur and does occur in all animals.
Sometimes at the moment of birth, sometimes later for others. Rarely does anything like the human family occur in other animals.