You could... I dunno... Hang out with Ibelin more. I feel like the complete lack of interaction between MC and her is making it just a little obvious that she considers her as more of a shield than an actual friend. Plus she hasn't told Ibelin or Arwin about the whole 'Garnet wants me to be a backstabbing bitch and will probably kill me if I say no' issue. Telling Ibelin would establish firm trust and potentially solve the issue through her relation to fish 1 and 2, whereas telling Arwin would probably just... solve the issue.