She is saving his life. If you don't understand: the jewel that was given to the mc was from the assassin, the assassin said it would help them find out who the culprit is, the mc made a plan: first she would introduce the jewel to the people at the top of the noble hierarchy, then she would tell them a story which would make the people more curious of where it came from, last people who so desperately want the jewel will go through a lot to find out who made the jewel. After they find that person, they will interrogate them hoping it will help them save the prince and find the culprit.
Ah, I see. Thanks, I got it.
You're welcome (▰˘◡˘▰)
I thought she will save his Highness's life and be with it. But it's getting so stretchy Idk anymore, I will just enjoy the plot and won't wreck my brain.