Sometimes the real excitement starts after the cameras stop rolling!
In Hollywood, it's commonplace to fall in love with a co-star -- and sometimes the love lasts long past the red-carpet premiere. (Power couple Blake Lively and Ryan Reynolds first met on set of 2010's "Green Lantern"!)
But more often, co-star romances are short-lived and, in retrospect, super weird. Check out these celeb pairings you probably forgot about: