The Royal Her by Sophie Stern

My coronation day was supposed to be the most magical day of my life. After all, I’ve been waiting my entire life to become queen. There’s no one better suited to rule over Draco Patriam – Dragon Country – than me.
If you talk to my twin sister, you’ll hear a different story.
This time, Ruby has taken things too far. She’s used magic to keep me out of the magical borders that surround our home.
And she’s separated me from my mates: all four of them.
Hot, sexy, and completely enamored with me: my dragon-shifter mates are everything a girl could ever want, and I can’t get to them because of my evil twin.
Now the clock is ticking.
I’ve got one year to find a way inside the magical borders that surround the castle and save my mates. Otherwise, we’ll be separated for all eternity, Ruby will rule the dragon world, and me?
I’ll be stuck in the human realm.
I can’t let that happen.