The Encanto's Daughter by Melissa de la Cruz

A young woman claims the throne of a realm inspired by Filipino mythology in this YA romantic fantasy, the first in an enchanting new duet by #1 New York Times bestselling author Melissa de la Cruz.
MJ Rodriguez has spent her life hiding in the human world, keeping a heavy secret: She's half-encanto. As the only child of King Vivencio of the Sirena Court, she's also next in line for the throne. And now, upon her estranged father's sudden death, MJ must claim her place as rightful heir.
In wondrous Biringan, the road to the throne is paved with thorns. Without a reigning monarch, the realm has spiraled into disarray. MJ has to win over a backstabbing council that objects to a half-human ruler. And when it looks like her father's passing wasn't natural but possibly inflicted by a curse, she must hunt down the sorceress behind this merciless magic.
In a bind, MJ forges an unlikely alliance with the striking Sir Lucas of the feared Sigbin Court, and soon, she loses her heart to the mysterious knight. But with peril looming over Biringan, the princess must decide if she can both open herself to love and carry the weight of the crown.