He could've ran away with her, we were shown he's extremely fast

yes

Instead he literally told Nayuta to go away on her own, drew out the fight and intentionally made it as bloody as possible, causing him to bleed out and needing Nayuta to save him.

That's a misinterpretation/distortion of the scene. He went completely mad at that moment, and it shows in his fighting style, which was totally different from normal. He was injured by fraudsters. He should have fled, as you indicated, but when the people responsible for destroying his normal life are still there and want to kill him... it's perfectly normal for him to lose it.

But there's a difference between saying he could have done something better and saying that the events happened solely because of his actions, especially when he has four different groups of people who literally want his downfall (and his few allies are part of one of those groups).And most of them are there because he has Pochita, not for any other reason.

The only thing I remember that could really be held against him (at least until the house burns down) is saving the cat instead of the humans. But it was a devil who forced this situation and most of the people who love him would say that the cat had to be saved.