Because he doesn't really love you unless he gives you an ALL-DIAMOND RING, like this one from Shawish Jewelers of Geneva, Switzerland.
This is the professional photo taken of my custom designed engagement ring! It was designed after the Zora's Sapphire from Legend of Zelda: Ocarina of Time! My fiancé and I are huge Zelda fans, and of course, our wedding planning is already Zelda-theme centered! He proposed to me on May 29, 2011 while we were on vacation!
Score another one for Team Zelda-is-the-Most-Romantic-Game-EVAR.