Royal Heir - Traci Hunter Abramson

Within a fairy-tale palace overlooking the azure waters of the Mediterranean, Princess Cassandra of Sereno leads a charmed life-until that life is nearly cut short in an assassination attempt. Desperate to protect his daughter, the king sends the princess to safety in the one place he trusts: the neighboring country of Meridia. There, Cassie's life is placed in the hands of a man who possesses the skills to protect her. CIA agent Levi Marin has years of experience pretending to be someone he's not, but posing as the boyfriend of a real-life princess is new, even to him.
With the CIA and Interpol hot on the trail of the assassin, Levi and Cassie do their best to blend in in Meridia and to remain professional amid their charade. Yet despite their best efforts, the charade begins to feel all too real. Their chemistry is undeniable, but forgetting the dangerous reality of their situation could prove a deadly mistake. Cassie's would-be killer is still at large, and her search for answers is leading her ever closer to a shocking revelation that will rock the monarchy of Sereno to its core.