Werewolf hunting is practically in Jessica's blood. Since the 1700's her ancestors have been hunters, and very skilled ones too, they despised werewolves ever since the war of the red moon.
Jessica didn't hate werewolves though. She was a werewolf. Ever since her parents found out she had to hide it. She took pills to weaken her wolf, preventing her from turning.
Jessica knew she was getting a mate. That's what the moon goddess was for, right? But Jessica also knew she had to kill her mate to be accepted by her family.