A Spanish translation is available for this game at https://galaxgyuscan.wordpress.com/sweetest-valentine-otome-espanol/

As it's a patch, you'd have to download the original game here, then download the patch in the website above (don't worry, the website nor download isn't malicious or has any viruses). For more detailed instruction, please head to Galaxgyuscan's wordpress.

Lastly, thank you to Galaxgyuscan or Beomnie for translating! They also translate some manhwas to Spanish, feel free to check their work if you're interested!