Lena Dunham won't get married until gay marriage is legalised across the US.

The 'Girls' star is very happy in her relationship with Fun musician Jack Antonoff - who she was rumoured to have got engaged to following an Instagram post of a ring - and she sometimes thinks about tying the knot but she's adamant she will not walk down the aisle until her lesbian sister Grace has the same legal right to wed as she does anywhere in America.

In an interview with the new issue of Grazia magazine, Lena said: ''It's really important for us to wait, because we both have a lot of gay friends and the idea of skipping ahead of them doesn't feel good to us.

''I don't want to do something my gay sister, Grace, can't do in a number of states.''

Lena and Jack sparked speculation they had got engaged after posting a photo of her wearing a ring on her wedding finger, and she admits her and Jack's pals were disappointed when she told them she wasn't a bride-to-be.

She said: ''It's a friendship ring, one of a stack of three that Jenni Konner [co-writer] and I have collected over the last four years.

''Jack's friends were texting, 'Congratulations on the big news.' Finally I had to say something because soon people were going to start getting offended that they weren't invited to our non-existent wedding.''

Although marriage is occasionally on her mind, Lena, 28, insists having a wedding isn't high on her list of priorities.

She said: ''There are lots of things I'm obsessed with, but marriage isn't my be-all and end-all.''