As much as she trusted Fenrir, she was bothered that after making her a promise that he wouldn't leave her, he obviously left her alone long enough to find her husband. Considering that he was in hiding, it couldn't have been easy. He was probably gone for hours. What if Rodolphus or Rabastan came looking for her there while she was unconscious? Her friendship with the werewolf wasn't a secret. She would've been vulnerable. Why would he lie to her? Sensing she was working herself up into a state of agitation, Antonin kissed her palm again.