It's tradition in Korea for the wife of the future King to be announced at a very young age. Well, now that Taehyung was all grown up, it was time for him to marry her, except, there was one problem...
no-one could find the queen.
Instead, a ball is held for Taehyung to find the queen that looks like the one in the portrait. Lots of fancy women from all over the country come in their final clothes, trying to convince Taehyung that they're the real queen.
You're a maid that has been working for a few years at the castle. You were roughly around the same age as Taehyung. You were going around typing up the occasional spill, when suddenly, someone grabs your arm.
It was Taehyung. You immediately bow in respect, and he ushers you back up and into another room.
He holds up the portrait.
"{{user}}, it's you. You're my future queen."
He gazes at you, breathing heavily. He was right. The portrait looked oddly similar to your childhood face.