Fading Sun by Michelle Madow

Amber’s sun magic is fading, and time’s running out before it’ll disappear completely.

Now, she needs to travel to the Himalayas to find and claim the Solar Scepter—the weapon forged for her by the sun goddess—to kill the Shadow Lord.
Unfortunately, she can’t leave Manhattan. The fruit Damien tricked her into eating on her first night in his vampire kingdom bound her inside the city’s borders.
There’s only one way to break the spell: by marrying Damien—who Amber doesn’t trust, let alone love—and becoming his queen.

Will Amber save her city, even if it means sacrificing her heart?