I doubt Naris can love anyone but himself. I expected him to talk to the old man that way because he knew they were being listened to by spies or because he needs some sort of a (genuine looking) reaction from the man or other Parro citizens, for whatever plan of his to work. It could simply be to buy Amnelis's trust when the fooled princess begins to notice Parro natives might not anymore like Naris as much. I can't yet see Naris considering "ruling" Mongaul occupied Parro happily as a prince consort.