Mary-Kate Olsen and fiance Olivier Sarkozy attended a book signing in New York City on March 10, 2014. Credit: via AP Images

Here come the future Monsieur et Madame Sarkozy! For the first time since Us Weekly exclusively broke the news of their February engagement, Mary-Kate Olsen and fiancé Olivier Sarkozy attended an event together on Monday, March 10. The newly-engaged duo was spotted at the book launch party for Bob Colacello's Holy Terror: Andy Warhol Close Up at the Diane Von Furstenberg Studio in New York City. 

Olsen, 27, and Sarkozy, 44, posed together for photos as the former child star showed off her giant vintage engagement ring. Olsen's hubby-to-be wore a navy suit, while she stayed wrapped up in a black overcoat, thick scarf, and oxford shoes. 

This isn't the first time Mary-Kate's proudly flashed her bling. Last week the designer was spotted out with sister Ashley and her sizable new accessory at Paris Fashion Week, attending Nicolas Ghesquiere's first show for Louis Vuitton. 

Olivier, the half-brother of former French president Nicolas Sarkozy, was first linked to Olsen in 2012. Since then, the couple hasn't been shy about their romance, frequently attending New York Knicks games together. 

"Mary-Kate's family thinks Olivier is the best thing to happen to her," an insider told Us of the former Full House star. "They love him."