King Willem-Alexander of the Netherlands and Queen Máxima of the Netherlands met in 1999 under relatively normal circumstances at the Seville Spring Fair in Spain (via Nine Honey). Willem-Alexander introduced himself to Máxima simply as Alexander and didn't make her aware of his status as a royal, let alone the heir apparent to the Dutch throne through his mother, the former Queen Beatrix of the Netherlands.

Having been born and raised in Argentina, Máxima wasn't as aware or clued in on the Dutch royal family as those in Europe or the Netherlands (via Hello! Magazine). So when they started dating, he spilled the beans, and she reportedly didn't believe him (via Dutch Review).

While their meet cute at a Spanish fair seemed spontaneous, Euro Channel noted that some reports at the time suggested that Máxima's father, Jorge Zorreguieta, and Willem-Alexander's grandfather, Prince Bernhard, had actually arranged the meeting in secret. Whether this did or did not happen seems to have been unbeknownst to Máxima, who didn't tell her parents that she was dating a prince. "I would tell them something different (about Willem) every time," she told Hello! magazine, "but at some point there was nothing for it than to say: 'He's the Prince of the Netherlands.'"