The Wiki says Arica may steal your supplies and leave if she becomes broken, but for both me and my brother it happened while she was "just" sad which I assume is a bug? And on top of that I had her on guard duty along with another survivor, with all upgrades to shelters comfort and safety, so it doesnt make any sense to me.
I worked sooo hard to get tons of meds and food by sneaking and killing the bandits/military who had a lot of supplies, so needless to say I got quite pissed when she took ALL my meds and food with her. If this is supposed to happen dispite her happiness level, you should at least have ways to prevent it by having certain shelter upgrades or multiple guards.