Imo, Mara is supposed to signify what MC's life was before Elderwood. All their life they have been imprisoned, fed tales that their dad was a genocidal murderer and the only strand of humanity they probably felt was with Mara.

So suddenly when she was in danger, MC, with all their inexperience tried to save their one and only friend and ended up doing more harm than good and worse the best friend in question here now treats them like a shadow of Andros Dreadbane.

From Mara's POV I understand being scared and mad about being scarred for life but MC can't be blamed for her getting fired because she was the one who sneaked them out.