The creator, director, producer and writer of the hit HBO comedy drama, which also stars Alison Williams and Adam Driver, told an audience at a Sundance Film Festival event on Friday (22Jan16) that she didn't want the series to "soften" over time.

"We were always conscious, especially because the show has been at times such a lightning rod, of overstaying our welcome," she said. "We've been very blessed to have the experience of people continuing to engage in the show in a really kind of rabid way after four - heading into five - years.

"We wanted to make sure we kept the momentum alive and didn't allow it to soften over time."

Lena revealed that ending after the sixth series makes sense, as the female-centred show would lose its meaning if it were to keep going.

"I was 23 when I wrote the pilot; I'm gonna be 30 as we shoot the sixth season. And it just felt as though, if we were to continue on, it wouldn't be about what it was originally about.

"It would be the equivalent of moving them to California, only California is them getting married and having kids and stuff like that. It just feels like at this point, it makes sense for us to wrap their stories up."

Lena joked that it was the success of some of the show's cast that made her want to end the series, and hinted at her co-star Adam Driver's huge popularity after his turn as villain Kylo Ren in Star Wars: The Force Awakens.

"These birds have to fly! They're all in Star Wars and stuff. They're busy!" she laughed.

Lena is at the film festival as a juror and to also promote Suited, a documentary about Brooklyn lesbian, gay, bisexual, transgender and queer (LGBTQ) tailoring company Bindle & Keep, which she produced.

The fifth season of Girls is due to be aired on in the U.S. next month (Feb16) and the sixth and final season is slated for broadcast in 2017.