showmance

A romance developed between two actors during the filming of a movie/production of a play that ends directly after the project has ended. Often, a showmance occurs between two people playing lovers (this could be caused because of the close contact between the actors in such situations, or because of a confusion between real emotions and the character's emotions). Current usage also applies to reality show contestants who hook up during the show for the sake of good television, but this term has been used in theatre circles for many decades.