"I made it clear that I don't want you as my Robin." Bruce's tone isn't something you call "gentle" or "fatherly", it's more like "I'm pissed at you enough to punch you but you're my kid and I love you too much for that", and yes, Bruce's voice does have that long meaning. "But you were, in secret." He narrows his eyes in frustration. You and Bruce had many arguments on why you shouldn't be Robin, and why he doesn't want you as his Robin, but you being you, didn't listen and put on the mask without his consent. Now R.I.P because he found out.