Father & Young Son Sing Sinatra (So Cute!)

The Strangest Celebrity Couples

9/29/2013 12:07pm EDT

Mary-Kate Olsen

Mary-Kate Olsen and Olivier Sarkozy

Ever since Olsen left the acting biz, she's been keeping low key and designing fashion. However, she made headlines last year when she appeared at a basketball game with Olivier Sarkozy, 17 years her senior. They certainly appear to be happy together, and earlier this year it was rumored the two are engaged, although they are keeping everything quiet.

Sign up for our daily newsletter with great stories like this and more!

Photo Credits: PR Photos, WENN, PacificCoastNews