Girls actor Andrew Rannells has admitted he feels “terrible that I wasn’t a better friend” to showrunner and co-star Lena Dunham while on set of the HBO sitcom.

Rannells starred as Hannah Horvath’s ex-boyfriend-turned-BFF Elijah Krantz in all six seasons of Girls, sharing most of his scenes with Dunham and delighting fans with some of the show’s best one-liners.

In her recently-published memoir, Famesick, Dunham – who was just 23 years old when she signed her Girls deal with HBO in 2011 – lifted the lid on numerous on-set struggles, most notably claiming Adam Driver was often hostile towards her.

Rannells has now addressed his co-star’s revelations, admitting to The Guardian: “That book is a great example of seeing things differently.

“Girls was my first TV job and when I showed up on set I saw the fun, exciting part. At times, Lena would open up to me and I’d read things in the press that were untrue or unfair.”

The Broadway actor continued: “But the book was hard to read as someone who is close to her now. I felt terrible that I wasn’t a better friend.”

Asked what he could have done to help Dunham, Rannells responded: “Been more available. I let a lot of s slide because so much was happening. I had a break-up, then a new relationship. I was doing The Book of Mormon eight times a week and working on Girls*.”

The first season of Girls debuted to critical acclaim in 2012 and the show went on to win two Golden Globes and two Emmys across its six seasons. The HBO sitcom also provided a launchpad for a number of future Hollywood stars, including Adam Driver (Star Wars, Marriage Story) and Alison Williams (Get Out, M3GAN).

In Famesick, Dunham recalled one on-set incident which allegedly saw Driver berate her for forgetting lines before throwing a chair at a wall.

The Star Wars actor, who played Hannah’s intense and unpredictable boyfriend Adam Sackler, was asked about Dunham’s claims during a Q&A at Cannes Film Festival in May. "I have no comment on any of that – I'm saving it all for my book,” he quipped.

Famesick also saw Dunham open up about her falling out with Girls producer and co-writer Jenni Konner, who she once counted as one of her closest friends.

Dunham, who lost weight during a period of disordered eating while filming Girls, recalled Konner once allegedly telling her: “I think the issue is that you’re too thin. And the thing is, it’s not funny if you’re too thin, it’s just Sex and the City all over again.”

Dunham wrote: “It was the first time [Konner] had switched roles, from cozy bestie with whom I bandied about ideas to the role she was initially pitched for: ‘supervisor’. Only the idea of a supervisor took on a more sinister note: Big Sister is watching you.”

Konner has not publicly responded to Dunham’s memoir.