The premise sounds like a Hitchcock film: a naive wife, a dashing husband with a secret dark side, a murder. Have Joan Fontaine report to the set, pronto! Except that, in contrast to classics such as “Rebecca” and “Suspicion,” where Fontaine honed her signature role as the spouse-who-belatedly-begins-to-have-doubts, Jean Hanff Korelitz’s thriller “You Should Have Known” features a heroine who has cultivated a clinical skepticism about relationships.