The Girls creator and star quietly began dating Antonoff early last year, and the guitarist was her date at Sunday night's Golden Globe Awards, where she was celebrated with wins for Best TV Series Comedy and Best Performance by an Actress in a TV Series Comedy or Musical.
Dunham admits she's proud to call Antonoff her boyfriend and unlike other young stars, she is keen to tell the whole world about her new love.
She tells Interview magazine, "I know there's some rule that you're not supposed to talk about your boyfriend publicly just because it seems like all starlets under the age of 33 have decided not to do that, but if you're in love with someone great, then I don't understand why you wouldn't tell everybody.
"You don't have to post naked pictures of them on the Internet or tweet pictures of your Christmas celebration, but I feel like, in a way, he's my best advertisement, so I'm like, 'Why would I not tell people who ask?'"
