(L-R) Actor Hayden Christensen and actress Rachel Bilson (R) attend the Costume Institute Gala Benefit to celebrate the opening of the "American Woman: Fashioning a National Identity" exhibition at The Metropolitan Museum of Art on May 3, 2010 in New York City.
They made it work for years, but eventually, it became too difficult for them to balance each other's competing interests.
From the sounds of it, Bilson may have been the one who called things off, as she decided it would be easier and healthier to move on.
Actors (L-R) Hayden Christensen and Rachel Bilson attend a cocktail party in honor of designer Kris Van Assche and hosted by GQ & Dior Homme at The Cooper Square Hotel Penthouse on September 8, 2009 in New York City.
(Photo by Michael Loccisano/Getty Images for GQ Magazine) Both of their careers have levelled in recent years, with Bilson most recently starring in Hart of Dixie and Christensen consciously pulling back from the limelight, saying he felt his career-defining role as Darth Vadar had been "a little too handed" to him and he wanted to focus on himself before trying his hand at Hollywood again.
Then this year, Bilson wished Christensen a brief but thoughtful happy birthday on Instagram, writing "Happy birthday, handsome." Apparently, Bilson was also close to Christensen's family, and spent a lot of time with them.