A Mexican soap-opera actor and philanderer gets his comeuppance in “You’re Killing Me Susana,” a romantic comedy that feels at times like a by-the-numbers exercise, but is partly redeemed by some decent jokes and an appealing performance by Gael García Bernal. Bernal’s Eligio is a charming rogue who earns his keep in the less elevated echelons of showbiz in Mexico City, and has no scruples about two-timing his wife (Verónica Echegui, who makes quite a fetching couple with Bernal), the Susana of the film’s title and an aspiring writer. Eligio eventually figures out that she’s taken off for Iowa, of all places, to attend a writing workshop at a fictitious university. Eligio is aghast to find that his wife is hitting the sack with another workshop participant, a large, taciturn Polish poet. [...] as attractive as the character is, there isn’t a lot of depth to him, and filmmaker Sneider never quite makes us care enough about what happens to the marriage. Walter Addiego is a San Francisco Chronicle staff writer.