Mistress of the Waters — Janeen O'Kerry

All Her Troubles
Born into a family of wealth and power, Shannon Rose Gray had to reinvent herself when her father's business collapsed. Planning to relocate to Ireland, the home of her forebears, after college, Shannon immersed herself in her studies. But when a strange gift revealed a mysterious scrap of vellum with musical notes and her name, she found herself whistling a different tune in a different time.

Yesterday
Suddenly in pagan Eire, Shannon found the sexiest man she'd ever encountered: Lasairian. Her senses ablaze with the beauty of the virgin land and the lighting of the Beltane fires, Shannon found herself enflamed by the virile Celt's touch. And when the feast's fires died and the morning dawned, the loving couple had joined. But there were things about Lasairian that Shannon didn't know. Was her handsome husband everything he claimed--everything she wanted? And the Beltane ritual--had it made her the prince's mistress by the waters near Abhain Aille, or the queen of his heart?