I’m sorry but Marielle Heller‘s Diary of a Teenage Girl (Sony Pictures Classics, 8.7) is another Schlumpies & Dumpies thing, or a movie about the sexual intrigues of someone I’d rather not contemplate in a sexual light, no offense. Set in the mid ’70s and based on a graphic-novelish, diary-like tale by Phoebe Gloeckner, it’s about an artistically gifted if somewhat homely girl in her mid teens (Bel Powley) who has an affair with her mom’s boyfriend (Alexander Skarsgard). It’s a fairly absorbing coming-of-age, finding-your-voice tale with a striking use of pop-out illustrations in the latter stages, but I simply had no interest in the sexual stuff. Some affairs are interesting and even fascinating; others simply are not. Powley is a fine, skilled actress with presence, but she probably needs to stay away from romantic material for the foreseeable future. Skarsgard is fine as the pathetic, oozy boyfriend, and Kristen Wiig does well as a fatigued, downbeat-attitude mom.