Jerry is not a very lovable character. He has a difficult time establishing a relationshipp with anybody. Since he is incapableof loving, it is not possible to be loved. In Jerry's case love is something he desires but he hasn't a clue how to get it. Since he can't have human love, he chooses the dog.
Jerry identifies with the dog. Neither of them are very loving or lovable. With the dog, Jerry can and does control the relationship. For Jerry it is about control. Love and control mean the same thing since Jerry really doesn't know what love is.