I Married A Prince by Kathryn Jensen

How could a small-town librarian with her nose in books — not the tabloids — know that the man she’d fallen for years ago was literally a prince? Or that their love child was heir to a royal throne? All Allison knew was that his seductive charm had turned her from a girl into a woman...

Unable to forget her, Jacob returned for one last taste of Allison’s sweet lips. When he discovered his son, he proposed a temporary marriage of convenience to save his family from scandal. By law, Jacob was not allowed to marry a ‘commoner’. But he was determined to bend the rules and make Allison a permanent princess by Christmas...