Actress Lena Dunham is holding off marriage to her rocker boyfriend Jack Antonoff until her gay sister can legally wed in the United States.

The Girls star has been dating fun. guitarist Antonoff since 2012, and while she has dubbed him her "life partner", Dunham insists she is not willing to walk down the aisle until her younger sister, Grace, can marry a woman anywhere in the U.S.

In an interview with shock jock Howard Stern, Dunham explains, "We're not against marriage but I wanna wait until it's something - my sister's gay and it just doesn't feel good to me to do something she can't do. She can do it in some places but not all places."

Since gay marriage is still not legal in 19 states, Dunham may have to way a while to tie the knot, but she feels confident in her relationship with Antonoff, even though they are often kept apart by their busy careers.

She says, "We met and the day after we were apart for three months and so our relationship was sort of formed long distance, like that's what I became used to. But now, for the most part, we see each other... we try not to be apart for more than a week or two."