Jim Carrey and Renée Zellweger, Me, Myself & Irene
The onscreen love story: After being left by his wife, good cop Charlie develops a coarse split personality, Hank. Charlie/Hank accompany Irene, a woman on the run from a pair of hit men. Irene falls for Charlie despite Hank's presence — but by the end of the movie, Charlie manages to eliminate his alter ego and ride off into the sunset with his girl.
The offscreen love story: Carrey and Zellweger began a romance after meeting while making this movie and became engaged, but they broke it off after a year and a half of dating.