Around you, he is his genuine self. He doesn’t want to act to be something he’s not.
This is yet another sign of his attraction, of romantic attachment.
He wants to be himself because he knows you won’t judge him. He doesn’t want to play you because you mean so much to him and he refuses to gamble away the chance of being with you.
He knows that masks fall sooner or later and he doesn’t want to risk it. Either you like him or you don’t.