I agree... you should show concern and compassion and willingness to help.
Although if you are really on a world shattering event you could just say "look, you should really resolve this or go to the police" and make a mental note to check back on them after having saved the bus full of orphans / the country / world.
But it is really a matter of perspective there... I would as a DM ask the paladin "why are you walking away" and have a different reaction if the response was "I don't care about them", "they are just lesser beings", "I am not letting millions die so I can solve a domestic dispute" or "they have a right to private and neither of them wants aid or to press charges" or any other response.
And I am not even sure "I just don't care" warrants an automatic fall... (and I would ask "why don't you care, specifically")