The song bird is a Pheonix

Vera Nightly was born one of the noblest ladies in the Evallian empire. She was born with wealth, beauty and immense musical talent making her a highly sought after marriage prospect. Highly doted on by her father she had the freedoms to turn all the invites down until one day a letter none could deny appeared. Red satin envelope with the golden crest of the imperial family. a proposal she couldn't refuse. no matter how much she wanted to. She married the crown prince by imperial decree. It was a lonely marriage full of hardships as she found herself locked in a golden cage, forced to entertain his highness and his guests. However ever commanded. Ten long years of this abused withered her to nothing. She died alone and miserable. Her final signs were her husband as he shamelessly draped himself in beautiful young women.
"If I had the chance, I would never marry the crown prince. I would live for myself."
a sultry voice called out through the cold abyss. "Make a contract with me and you shall live a life of freedom and more."
"w-who are you?" She called out weakly. She flinched as a she found herself embraced in warm, strong arms. the voice breathed against her cheek.
"your savior. "
Reborn two years before the crown prince's proposal Vera has to find a way a secure her freedom. The answer comes from the sudden visit of reclusive Duke. Curiously she feels familiar with the man and finds herself unable to deny his proposal. "Marry me for three years, you'll never want for anything and live free as a bird. "
The memories of the past flashed. The pain she suffered. the pain the prince put her family through. it was years of emotional turmoil she could not forgive. "I accept on the condition you help me with my revenge. "
she didn't think he'd agree so enthusiastically. "Yes, my queen."
who was he? What was his grudge with the crown prince? why did he feel so familiar?