Graves and Credence are together but Graves is painfully aware that he's much older, and that the magical world is very new to Credence and secretly he's counting down the days until he gets left.

Then Newt Scamander shows up and he has such an easy connection with Credence and makes him laugh so easily.

So he starts slowly pulling away even though it's killing him for Credence's sake, doing things like giving Newt a shovel talk (he finds it weird but chalks it down to being autistic) tells Credence it's ok if he wants to go to England (Credence thinks he means together so he blithely agrees) until somehow everything comes out