Or is there a logic to the progression? Let's review it (and bear in mind that unexpectedness is rather subjective):
Why do family members fight?
Why do friends fight?
Why do strangers fight?
Admittedly, it's an easy progression to miss. Maybe it wasn't easy to make out, amongst the noise. Perhaps you felt another progression was more important. Well, there you have the answer then: you felt another progression was more important.
There's no shame in waging an educated guess and making a mistake -- shame however doesn't quite capture the beast when intellect and energy are applied toward maintaining a miscalculation.
Honesty hurts no one but the dishonest.
Part of the series: Narcissa