There's plenty of blame to go around, but overall, this is the kind of problem that happens when therapists don't exist. People don't realize how severe these types of things are. Marriage requires proper communication, and a wife really needs emotional support when they are pregnant, and even after they gave birth.
Harsen never being there and even bringing in a bloodied body upon his return after a long absence when his wife is still pregnant will definitely hit her mental state quite strongly. And never being there definitely did not help Ercella's mentality. She just wanted her husband to comfort her emotionally, and he's been failing at that. Of course, Ercella acting out and neglecting her child is still something that isn't right by any means, as the child suffered as a result of Ercella not being there for him.
There just needs to be a serious conversation between Ercella and Harsen so that they can understand one another.