Eren felt that Aleph made one horrible mistake in the past.
This mistake was way bigger than the mistake he made by trusting the Slumbering Goddess. It was the fact that he didn't accept his abominated divinity himself. He didn't embrace it. Not really.
Aleph did what he did and conquered Hell to bring a semblance of peace all across the boundless cosmos. And since he conquered it, it was inevitable that it would belong to him.
However, his act broke the fine balance that had been established between the demons and gods since time immemorial. It meant that his success had a completely opposite effect from the one he had set out to achieve. It was as if he was being criticized for being an overachiever.
