Touched by Magic by Doranna Durgin
Reandn is a guard in the service of the high king, with a respected position, a beloved wife and a son who adores him. Until, that is, he investigates the mysterious disappearance of children from the castle grounds, and his life is torn apart by magic. But magic is not supposed to exist, and only Rethia, the healer, believes in Reandn's outlandish tale. As a child herself, she saw the unicorns leave, taking the magic with them. Now, the unicorns want to bring magic back into the world. Except that Reandn, who knows that harm that magic brings, will do whatever lies in his considerable power to make sure that his life is never again ...touched by magic.