Love on Set: 13 of TV's Hottest Co-Star Couples

Are you starting to see a pattern here? Leighton Meester (Blair) jumped on the Gossip Girl relationship train in 2008 with co-star Sebastian Stan, who guest-starred on the series as bad-boy Carter Baizen. Like her co-stars, she called things off in April 2010 — around the same time Ed and Jess encountered breakup numero uno.

Despite being linked to her Country Strong co-star Garret Hedlund and Going the Distance funnyman Justin Long (she made a nanosecond-long appearance at the beginning of the rom-com), the Queen B is stayin’ single. For his part, Sebastian Stan may (or may not) have had a fling with Glee star Dianna Agron (Quinn).