Interestingly enough, the fact that she got this red eye without visiting Homaspernia unlike Kendra undermines the theory of Hell kingdom influencing it's citizens, because that would make no sense for Maryen having such a "curse" out of nowhere.
Also I'm not sure that it's just her eye that is responsible for her behaviour. How would that even work anyway? The eyepatch supresses her power mostly, at least that's how I understood it. Or maybe it supresses the "dark side" of Maryen, her inner Neyram, that is yet strong enough to drain this amulet over time. In any case, having an eye physically ripped off won't change much I assume.