If you have love with a sentient being, it is not beastiality.
Not strictly true.
Bestiality by definition is love with any animal that isn't a human.
Therefore, having love with any member of the Animal Kingdom, besides another human, would be bestiality.
Regardless of sentience.
It's a coincidence that no other animals are sentient, and that having love with them is bestiality.
It's also true that if, for example, an alien creature were to land on earth, and you were to have love with it, and it were fully sentient, that your love would be considered both bestiality and xenophilia.