Lemme explain further.
Becoming a Leshah is considered the greatest honor among servants because they can serve Amon further than any servant could IF Amon takes a liking to them. They say they are the first to be taken with Amon to the after life after his lover. (Someone might have to fact check on it but that’s the gist of it in the first few chapters)
You've got most of it right, lol. They're actually higher than ordinary servants. Leshas are the companions and concubines of the Sha, but they never really served them in that way.
Amon and Na-in would never have any romantic feelings for any of the Leshas. Amon is terrifyingly obsessed with Na-in, and he sees humans as nothing more than worms. Na-in would get jealous whenever another Lesha was presented to Amon, but Amon never cared about any of them.
Most of the time, if a Lesha was suspected of being favored by or getting too close to one of the Sha, they would be executed. The official reason was that they had been chosen to serve the Sha for eternity, even in the afterlife. But that's not true either, The temple teaches the Lesha (and society) that being "sacrificed" or dying early ensures they get to serve the gods eternally in a gorgeous afterlife. But its just brainwashing lie the high priest made just to have power or control.
Na-in knows about this, that leshas are being killed if they get too close to him, so not only does he feel betrayed about what rue did, he's scared about losing Rue at the same time
Mc is still priority lol.
Rue has just gained “nobility” in a sense. He’s no longer has servant duties like he did before. Instead he can get served by the temple servants and focus on pleasing the gods personally whatever that may be. He also has (in a sense) more privileges to Amon and Mc.
From what I understand Rue became a Leshah to get noticed by mc or stay close to him. (U might need to fact check me)
He doesn’t want to get abandoned.

Can someone explain my stupid ass what rue did in the end???