Filmmakers can’t seem to stop making movies about ill-fated couples. Literally ill in the case of our leads in the upcoming hospital romance Five Feet Apart.   Audiences ain’t masochists. But we keep returning to the cinemas to vicariously experience the agony of lovebirds torn apart by a fatal disease. In other words, a relationship with a looming expiration date. You’re probably familiar with the story: either one or both of…