Lena Dunham cheated on Jack Antonoff after he started spending time with ‘teen pop star’

Lena Dunham has detailed the end of her relationship to Jack Antonoff (Picture: Dan MacMedan/ WireImage)

Lena Dunham has revealed she cheated on Jack Antonoff with an old flame from her teenage years.

This week the Girls creator, 39, released her second memoir Famesick – in which she hasn’t held back sharing details of her professional and personal life.

One of the most jaw-dropping admissions in her book comes with her detailing the breakdown of her five-year relationship with the music producer and Bleachers frontman Jack, 42.

The pair dated from 2012 until 2017.

However nearly a decade on, Lena has now looked back at the end of their relationship and revealed she cheated on her then-partner – wh...