I had a 12 yr old german shephard boy, and a 9 yr old female. The boy died 2 weeks ago. And in the last 2 weeks, the girl would not eat, would hide all day, and barely drink water. We found her dead this morning in a corner of our yard, but she was 100% physically healthy.

Did she die because she couldn't live without the boy she spent her whole life with. They were never separated for even 5 minutes her whole life.

It's possible she died of grief, but get a necropsy done to make sure there's no disease (like parvo) in the area before you get another animal.