Saria doesn't understand why Lucien mess with her feelings so much. Maybe it's because he's so seductive and was the first man to kiss her, or perhaps it's because he manages to be so mysterious while being so straightforward.
Anyway, when she's with him, she can't think about anything but him, and every interaction with him feels like magic. That makes her feel so silly, but it's an exciting pleasure, unlike anything she's ever experienced.
From above the clouds, Nea watches her daughter's eyes sparkle as Lucien flirts with her. The magnificent Mermaid Queen can't help but smile as she is also a mother and is delighted for her daughter being happy.
Though she still has a lot of doubts about Lucien and his sinful group, as well as not believing he could be really good for her people, Nea isn't against him making Saria happy, at least for a little while.