Dorfman theatre, London David Eldridge's two-hander depicts the difficult conversations that follow one partner's cancer diagnosis David Eldridge's trilogy has travelled across the early and mid stages of coupledom to come to this finish. The play marks the end of an era in more ways than one. Programmed in Rufus Norris's final season as the National Theatre's director, it is also a farewell for the couple at its cen…