Lena Dunham describes her longtime boyfriend, fun. guitarist Jack Antonoff, as her "life partner," but don't expect the couple to tie the knot anytime soon.

"We're not against marriage," the "Girls" star tells Howard Stern in a new interview. "But I wanna wait ... my sister [Grace] is gay and it just doesn't feel good to me to do something she can't do."

Dunham previously about her sister earlier this year while accepting the Point Foundation's Horizon Award for her LGBT advocacy work in New York.

" My sister's process of coming to terms with her sexuality was as angst-free as anything involving sex can really be," she said at the time. "She was assured by the adults in her life that she was not only accepted, but adored for who she is."

Dunham made a similar pro-gay marriage vow at the 2013 Golden Globe Awards.

"I don't want to get married until all gay people can get married," she said at the time, according to the Daily Mail.