The game is so freaking pretty! The way the animation looks is so flawless. I feel super jealous of seeing an UI like this.
Anyway, the story was short and sweet. Though I am a bit confused about the age of the characters. From the writing, it seems like they are both children (I'd say around 10-12 or so), but there is an arrange marriage happening within a week? Or did the story leaped a decade or so between Sol meeting Luna? That seemed a bit peculiar to me.
There were a few instances of typos/grammatical errors and some little issue with the code. ("I love you, please don't leave me alone."\"Don't leave me alone, please!") appeared as is on the screen (I think you prob wanted to code that?). $sun.coloreyes didn't show a value to me, just the variable name. "You should stop meeting them," appeared even though I didn't tell my parents about Luna. (did I miss something? Did Sol mention it at one point anyway?).
This was a nice short game :) Thank you for creating it!