Maybe they had another significant other at the time, or maybe their friendships became more romantic over time. Check out the couples who worked together and managed to hold off on the sparks... for a while at least!
Rumor has it that Orlando Bloom is bouncing back from his split from Miranda Kerr with his co-star from the Lord of the Rings movies, which came out ten years ago.
They started playing a couple when she was just 14 to his 20 on That '70s Show, and fifteen years later they're a couple for real!
Gossip Girl castmates Ed Westwick and Jessica Szohr were best buds for a year before they started dating, with Jessica admitting the transition was "a little awkward."
You can't blame a then-married Jennifer Garner if her co-star Ben Affleck caught her eye during filming of their 2003 movie Daredevil. They married in 2005.
Glee co-stars Lea Michele and Cory Monteith dated other people for the first three years of their friendship, and finally became a couple in 2012.
Peter Facinelli and new girlfriend Jaimie Alexander worked on a film and a TV show together before finally taking their friendship to the next level after he split from wife Jennie Garth in 2012.
For their first several years of working together on Melrose Place, Laura Leighton was dating around and Doug Savant was married, but soon after his divorce they got hitched.
Garth Brooks says that he fell instantly for fellow country star Trisha Yearwood upon meeting her in the '80s... but he stayed married to his first wife for thirteen more years. The power couple married in 2005.
Lauren Graham and Peter Krause's romance on the set of Parenthood wasn't the first time they flirted on set. They were on an episode of Caroline in the City together in the '90s!
After her split from One Tree Hill co-star Chad Michael Murray, Sophia Bush moved on to... her other co-star, James Lafferty!