the former king juan carlos ii had a long-running affair with a german socialite during the final decade of his reign .
but if felipe and letizia were upset about the revelations , they certainly were n't showing it as they arrived at the university of alcala de henares to present the cervantes prize for literature .
later , as a group of ukulele-wielding students appeared to serenade the royal who has been attempting to overhaul the image of the monarchy in spain since taking the throne .