Circulation Supervisor Cándida Miniño recommends Immortal by Sue Lynn Tan.

Immortal is a beautiful standalone romantasy with an enchanting cover that succeeded in luring me to peruse the book.
Liyen, the heir to the land of Tianxia, is the main character in the story.
The land of Tianxia guards the borders of the immortals from other mortals’ incursions and is in exchange protected by the immortal queen from netherworld creatures.
When Liyen is poisoned, her grandfather, the lord of Tianxia, steals a sacred lotus to save her life. The immortal queen sends the merciless God of War to retrieve the stolen lotus, attacking Tianxia.
Liyen’s grandfather dies, and now she must negotiate the freedom of her people from their warding duties when she goes with the God of War to the immortal realm to pledge her loyalty to the immortal queen (all while keeping her possession of the lotus a secret).
Liyen is assigned the protection of the God of War, and while getting to know him, starts fearing she might lose her heart.
More troubles and secrets follow as new threats appear. Some of the secrets will not be unveiled until the end of the book. When they are revealed, the pieces of the puzzle fall into place, allowing the reader to understand the whole picture.
The book is full of magic, action, and creatures from legend.