The Royal House of Niroli Series by Susan Stephens

Prince boss, virgin secretary...unexpected heir! The prince with a provocative past has returned to claim Niroli's crown... Nico Fierezza has never relied on his royal name. But now the king has summoned him. Niroli is ready to welcome its new ruler! Carrie Evans has been in love with Nico, her boss, for years. But he ruthlessly discarded her after one night of loving and now she's pregnant! Carrie will do anything to protect her baby's future. Does anything include marrying Nico?