“P.S. I Love You” looks squeaky clean and utterly straight and very much removed from the shadow worlds in which Ms. Swank has done her best work. Yet as directed by Richard LaGravenese, who shares screenwriting credit with Steven Rogers, it has a curious morbid quality. Ms. Swank plays Holly Kennedy, a 29-year-old New Yorker who, shortly after the story takes off, becomes a widow. Her husband, Gerry (Gerard Butler), however, doesn't fully disappear. Instead he visibly lingers in her apartment — he seems less like a ghost than like a manifestation of mad grief — and in the letters he left behind. These letters are full of bossy instructions for Holly on how to grieve and live. They are, in essence, a primer on how to be a widow. __
