A Voice for Princess

The main character of 'A Voice for Princess' by John Moressy is Kedrigern, the wizard, and a specialist of counterspells, who get annoyed with Wizards Guild for their cooperation with alchemists and started living alone in his home. After a time, he discovers how boring a lonely life is, and goes in search for someone to marry. Finally, he finds Princess enchanted into a frog, and he takes the charm from her, but it turns out, that giving her back a human voice will be more difficult...