It is a pleasing irony that Marriage Story begins as the legal union of the title is effectively at its endpoint. Theater director Charlie (Adam Driver) and actress Nicole (Scarlett Johansson) have been married for several years, working together on abstract plays and parenting a son, Henry (Azhy Robertson). But Nicole has decided she’s done, and what’s initially a fairly amicable split rapidly turns bleak and vicious, with each party losing sight of the things they like about the other and forging — with differing degrees of success — a vision of themselves outside the complicate, sometimes codependent partnership. With bruising wit and aching empathy, writer-director Noah Baumbach charts the unruly waters of modern divorce, including the calculated savagery of attorneys who specialize in the courtroom gamesmanship of uncoupling. Bolstered by the crisp cinematography of Robbie Ryan, a lovely score by Randy Newman, and a fleet of winning performances across the cast (with particular nice work from the trio that comprise the legal representation: Alan Alda, Laura Dern, and Ray Liotta), Marriage Story lays bare the compromises and unkindness that manifest when people who once pledged eternity now find themselves reconstructing adult lives from the shards of their broken promises. To his great credit, Baumbach doesn’t take sides and doesn’t prod the audience to do so either. (Online cineastes who conspicuously identify a hero and villain in the film are submitting their own Rorschach test answers for the world to ponder.) He is a mere chronicler of dismay, showing all the bruises and gently, soberly suggesting that they might eventually heal.