Eren's depression

Eren is depressed because he literally is kind of a God but without power to change anything but only to see the future.

He could see the future so his life became boring,knowing what will happen next is BORING as fuck.

Mikasa comes to you with icecream. Boring I know how it tastes.

You attack Libero because you can't change anything.Boring.

You know Sasha is going to die but you can't change it.Boring.

You destroy the world to see that scenery.Little less boring.

He finally wants to see something that he doesn't know will happen and IMO it will be after "That Scenery"

He is moving forward just to see something beautiful in the end that will make him cry just like he did in chapter 1 after waking up instead of looking at people dying all around him just to save him all the time.