We and wolves grew up together. They learned that if they stay close to us they get fed. We developed a symbiotic relationship. We fed the craps to the wolves. They got closer, more domesticated. This relationship developed slowly and trust was built.
I don’t think we have this relationship with a lot of the animals we eat. It’s not that we aren’t compassionate and empathetic for them, but their purpose is for us to eat them. They pose no threat to us, except the wild boar. For the most part they are not particularly vicious.
We domesticated them for food, not mutual benefits. We fed the wolves, they didn’t kill us, and later they helped us hunt. We evolved together. That’s why they are often referred to as “man’s best friend”.
Trust. They started to trust us and we them. They sleep at our feet, and we pet them. At some point the friendship became more than just a symbiotic relationship. It is now a relationship of trust. We could go days without them “doing things for us” and the bond would be just as strong. At the end we have built a social contract with them.