You Are My Destiny.

Rasika is a modern girl who is self-confident and likes romantic novels, especially when it has time travel. One day, she buys the novel Dan Phromlikhit Rak and somehow finds herself as Karakade, the heroine in the novel. Karakade lives in 1923 and is the daughter of someone with high status. She meets the hero and they fell in love instantly. The story describes the journey they go through in order to fulfill their love even though she already has someone she is supposed to be engaged to.