It's been a couple of years since I read this so I don't remember any names sadly.

Fantasy-esque world, royal-political drama, and full color? I don't remember the country of origin.

Girl MC tries to use her last chance to confess to her crush, the crown prince, by going through her dead aunt's alchemy book and concocting a potion that would allow her to enter his dreams. Unfortunately, her school rival drinks it, and she enters his dreams instead. She also hadn't read past the recipe as it would also kill the user eventually -- so she switched her post-academic career to research (I think?) to find a cure.

There might also have been assassination attempts by the 2nd queen (who has red hair). The 2nd queen had her son marry someone from another nation whose culture knew dark magic.

I hope this sounds familiar to someone else? TIA!

That's it! Thank you! 🙂