He wasn't ready.
He'd probably never be ready. He didn't know how to stop the nightmares that plagued his sleep. He couldn't stop the tremors that plagued his body every time he thought of her. He damned his eidetic memory for bringing her up every second.
Yang had gotten to him more than he had anticipated.
They want him to come back. He wasn't sure if he could. He doubted himself for the first time in his life.
But he'd go the only way he knew how; pretending everything was ok.