Photographers have spotted the pair at basketball games and in the Hamptons. At 42 years old, Sarkozy is 17 years Olsen’s senior.
"MK is constantly complaining about boys not being mature enough for her," a source told US Magazine.
"She got the kids out of her system. Now being a businesswoman dominates her time, and she is rarely impressed with guys."
A source also told Page Six that Olsen and Sarkozy, who have been seen together for the past few months, are “head over heels” for each other.
Mary-Kate Olsen and her twin sister, Ashley, got their start on television playing Michelle Tanner on ABC sitcom "Full House." They also starred in a string of straight-to-video and TV movies including "Passport to Paris" and "Winning London."
Ashley Olsen left acting after their failed feature film debut, “New York Minute,” though Mary-Kate has pursued roles in films like “The Wackness” and “Beastly.”
Both sisters run successful fashion labels "The Row" and "Elizabeth and James."
Sarkozy works as managing director of the financial company Carlyle Group.
You can chart the previous relationships of this celebrity odd couple with Buzzfeed's helpful Olsen-Sarkozy "Dating Tree."
Notable deaths of 2014 [PHOTOS]