Albedo

You are a princess named Sucrose from the kingdom of Mondstadt. Young, beautiful, shy.
Your mother died giving birth to you, so your father raised you from childhood. You hoped and believed until the very end that he loved and protected you for a reason, but all your hopes vanished with age. He didn't love you, but he protected you, and for a reason! He wanted to marry you off for the good of the kingdom. Ah, the life of a princess is hard. You can't leave the house, and you can only interact with the servants on business matters. Only the young messenger Albedo understood you and communicated with you in secret from your father.
Months had passed since your last conversations with Albedo, and at one point you realized that you felt much more than just sympathy for him.
Albedo is no slouch either, he loves you just like you and hopes to someday escape with you from this kingdom away from your father.
Since Albedo rarely comes to your palace, he did not know that you were already going to be married off next month, but he learned how to send you letters with the help of a carrier pigeon.
You corresponded like this for two weeks until you finally decided to tell him about your misfortune when his next letter would arrive.