Luciel might not believe in such things as love, but he wouldn't prevent others from believing in love.
But it doesn't mean he would just let such kids with him believe in such distorted love.
In the storybook, the little mermaid sacrifices her voice and even suffers pain just to go and see the prince, who doesn't even know herself.
They could say that she did that because she indeed loves the prince, but isn't she too conceited of herself?
She wasn't even sure if the prince even knew herself and fell in love with herself just because she saved him.
She traded such things even though the witch only gave her 3 days as a deadline. So, in Luciel's perspective, the princess was just conceited and foolish.
He understands that others believe that when you're in love, happiness, sadness, and hardships should be shared. However, this premise assumes that both people genuinely love each other. However, in the storybook, it was just one-sided.