Reign and Ruin by Devon Atwood

Anwen is the Faie Queen.
Armed with the shared power of Moros and married to the Faie King, she has narrowly escaped a gruesome fate at the hands of Erinyes, and has managed to trap two of the three sisters. But their trials are far from over. In a mountain far away, her brother, King Matth, languishes in mysterious agony. Close to her home, Ruin threatens to break free of the magical barrier that protects the humans and Faie refugees, but Anwen and Evander have no hope of trapping the vengeful sister without fulfilling the prophecy given to Anwen at her birth.
When the famed Iron Vice shows up at her gates, fully intending to save Anwen from the Faie he believes have invaded their vale, Anwen finds herself at the center of an ageless dispute between humans and Faie that could prove fatal to the war against Ruin. Desperate to save both people, Anwen and Evander discover that the answer to their salvation can only be found in the Pantheon of the Gods. That is, if they can live long enough to escape it.
Either Anwen will reign, or Ruin will burn them all.