What does the "Low NPC Lust" condition mean on the shopkeeper?
Means you didn't pick the lewd options on Luna's dialogues. Currently, there aren't any repeatable ways to increase her stats, so you need to pick the right answers at each interaction. I know this is not ideal, so in the next update you'll have repeatable ways to increase relationship and lust, as well as repeating some of the jobs to see the scenes again and earn more gold ;)