Swapped Fate: Loved by Poseidon

Isolde and her sister Cecilia are both reborn on the day blessed by the Sea God. Cecilia seizes the white light lottery slip first, marrying into the ducal household, while Isolde takes the golden light slip and marries Aegir, the poorest fisherman at the dock. Enduring hardship at the docks, she remains unaware that her husband is actually the incarnation of the Sea God. Though her sister repeatedly plots against her, the Sea God secretly intervenes to protect her. When the abyssal demon finally awakens and the Sea God's true identity is revealed, Isolde kneels before the altar, praying to restore the fading deity, and is thus crowned as the Bride of the Sea God.