“No more happy endings,” joked Lars Von Trier, still smarting from the beating he took upon the release of Antichrist. Late in 2009, the director said he was planning a science-fiction film about the end of the world, fueling speculation that the new one would be a departure from the dark, junk-crushing epic that had earned him such scorn at Cannes. But now that Melancholia is here, it plays like an obvious companion piece to the earlier film. There are some tweaks, sure. Antichrist depicted a marriage racked by a woman’s guilt, while Melancholia features a wedding wrecked by a woman’s depressive disorder. But both films probe the nature of depression and the ways it can inspire people to withdraw, lash out, and sabotage their own chances at happiness.