25. Leighton Meester and Sebastian Stan

Leighton and Sebastian dated for a few years after meeting on the set of Gossip Girl in 2007. Sebastian played recurring character Carter Baizen who sort-of dated Leighton’s character, Blair Waldorf. Sparks flew off-screen as well, and they seemed to really hit it off. Just when things seemed to be getting serious between the two, they split up.

Gossip Girl fans were surprised when they split in 2010, but both of them said the breakup was amicable. Over the years, Stan has dated several other actresses but has kept a pretty low profile. Meester is now married to Adam Brody, whom she also met when they worked on-screen together.