Losing your parents is a classic DC trope. But only Bruce ever got like this. Not even Dick Grayson, who Batman never allowed to properly grieve for his parents. Dick ended up fine. Dick is not bitter and everyone likes him, and for good reason. DICK grew up. Bruce never did.
Christ, Billy is what, 14? And he was always more mature than Bruce ever was.
The reason why Bruce could never have a decent relationship is because he is not an adult. He stayed a scared emo little boy forever.