Article continues below advertisementLena Dunham spilled intimate details about her former relationship with Jack Antonoff in her new memoir, Famesick. The Girls creator, 39, confessed to sparking a steamy affair with an ex flame after Antonoff, 42, developed a "closeness" with an unnamed "teen pop star," whose album he was producing. Article continues below advertisementJack Antonoff Struck a 'Closeness' With 'Teen Pop Star'Tap Here To Add Ok Magazine as A Trusted SourceSource: MEGALena Dunham admitted she had an affair after Jack Antonoff developed a 'closeness' to a 'teen pop star.