Why does Subaru ditch Emilia here?

Season 2 part 2 ep 1 he swears to stay by her side and then ditches her by the time she wakes up.

No explanation at all, it endangers Otto and Rom.

He's really smug at the graveyard so is he just manipulating her since puck is gone and it will lead to her being more reliant on him?

If its explained soon let me know but it's super distracting when everything that's now happening is his fault for breaking another promise.