Originally Posted by Why Are You Crouching Spock?
I think that is still his motivation, sacrificing his normal life is a byproduct which he is struggling with before she actually goes into hiding Like the scene when he's frustrated, drawing the suit throwing it in the fire or when he's at his parents grave attempting to plead with them. He can either move on or continue to live in the past giving up his normal life. In the end they both go down that path both ending up as solitary figures. Sure, it's because of a failed relationship. But thats more a final trigger for a motivation that already existed (for Bruce).
Well, Bruce's impossibility to have a normal life is that he's convinced Batman is necessary. But being about to quit before even starting his Batman mission... no thanks. I mean, that's a completely unnecessary new element that redefines the character. Bruce's parents being killed is not enough. I think Bruce has always been over women. A girl cannot be reason enough to prevent him from being Batman.
At least in TDK he had found a better man in Harvey Dent. And in BR Bruce was a soplitary and Catwoman was already what he was. I mean, in those movies, Bruce was Batman already so he knew what was he saying no to when he thought of quitting.