Adapted from the self-help book by Greg Behrendt and Liz Tuccillo, this amiable romantic comedy benefits from its stellar ensemble. Jennifer Aniston and Ben Affleck are a couple who live together but keep postponing marriage; Jennifer Connelly wants to have a baby, unaware that husband Bradley Cooper is cheating with yoga instructor Scarlett Johansson; and Drew Barrymore is a media professional overwhelmed by online social networking. The movie’s warm tone is set by the central character played by Ginnifer Goodwin, a self-deluding blunderer in need of straight talk from good guy Justin Long. Director Ken Kwapis (The Sisterhood of the Traveling Pants) has the right touch for this material, making pointed observations without spilling blood. PG-13, 101 min.