It's time to say goodbye already?

Hi all,
Our family adopted a 2 1/2 years old golden retriever a day before New Year. A week here with ample love and patience. But not a day gone by the lovely dog would not bite another dog, whether it's its playmate at home, or the neighbor's dog. DH decided that we must let her go. I'm so heart broken, but can't bear the though that this dog will seriously hurt other dogs.