Stardust and Sovereigns. Astra Vex: The Cosmic Ace, #3

Stardust and Sovereigns: A Chronicle of Astravex and Aurora    Lyra Vex was never meant to be a sovereign. She was meant to be a mathematician, a dreamer who coaxed constellations into equations. But when the empire fractures, her calculations become weapons, and her choices ripple across worlds.  Kael, once the shadow prince of Astravex, now stands behind her-not crowned, not armored, but bound by the gravity of what he cannot ignore.
His loyalty is no longer to thrones or treaties, but to the woman who teaches him that power means nothing unless it chooses what to orbit.  In Stardust and Sovereigns, love becomes an act of defiance, science a beacon of hope, and the fate of the galaxy rests on whether two people brave enough to fake a relationship are brave enough to make it real. "Two worlds, one orbit - where love and empire collide."