NEED HELP!

Okay i need help remembering the name of a manhwa!
Basically, its about a girl who devotes her whole life helping the duke become the crown prince, by using her summoning powers. But like when he finally became crown prince, she checked on him and realized that she was betrayed and instead he ended up liking her cousin. So she kinda like dies but goes back in time to a point before she devoted her life to helping him and decides she will get her revenge and break ties with him.
PLEASE!! IT HAS A REALLY GOOD PLOT!! I JUST FORGOT THE NAME!! I THINK THE TITLE HAD THE WORDS "Emotionless" Or "Has no emotion" or something IDK!! UWAAAAAA!!