Deffending my Kingdom against my Beast Friend

The Kingdom of Heavenly had grown, and so did the Royal Family. As Cryztalliene maintained her standing in the inheritance of the crown, the more did her Uncles pushed their eldest to take it from her. Ever since she was young, her parents helped her to maintain her power, but at the right time, they know that they can no longer help their little girl. She was challenge by her cousins for the crown, they need to retrieve the Monarch's Crown, it's the Crown of the first Royal Family in Heavenly Kingdom, and it holds the biggest diamonds in the world. By wearing it they could take the inheritance from her, but on the way to victory they were attacked by the Hiding remains of the beast race, that kept hiding in the Mount of Drought. Some were injured, some escaped, but some had no choice but to continue to seek refuge in the Monarch's Ruins. Cryztal will face her abductor, Syllian. Despite this two being so different they became friends, after Cryztal helped Syllian, and gained his trust. But in unexpected terms Cryztal accidentally drank from the waterfall of the witch, it's a cursed water that will make beings do things they never should've. At first they were relaxed when it doesn't seem to have effect, but Cryztal's relief ended when she felt something more than just friendship for her beast friend, the fountain made her fall in love with his beast friend. As the other Royals send reinforcement for the cousins stocked at the Mountain, they found out about the existence of beasts in their Kingdom. As they attack the beast they brought back the hundred years forgotten grudge between Humans and Beasts, they unleashed a war. Will Cryztal still be able to defend her Kingdom, if the enemy is her friend whom she loves? Who will she side with?