“Though Trainwreck is a robust comedy, ranging from genial to zingy to uproarious, it’s essentially a romantic melodrama of self-abasement, self-deception and self-discovery. Its subject is the proximity of pleasure and pain, of self-affirmation and self-doubt. Its resolution involves love, which, in Apatow’s view, is no renunciation or simplification, but just another mode of difficulty, a kind of fulfillment that emerges from characters who are already formed and who merely put themselves and each other to new tests.