"It's been a few months. I feel really lucky," she said at the time, before calling her beau – known professionally as Attawalpa – "the greatest person I've ever met".
They appear to have gone from strength to strength since.
In June, she celebrated her partner's birthday with a touching Instagram post, writing: "When I was 3 weeks old in downtown Manhattan, I had no idea a baby was being born in England (Winchester, no less!) who would rocket into my life – wearing a lime green polar fleece snood – and challenge so many of my beliefs about myself and the world with magical abandon."
Dunham was previously in a long-term relationship with music producer Jack Antonoff, opening up about her heartache from their separation last year.
The Once Upon A Time … In Hollywood actress revealed her mental health was at a dangerous point when she found herself engulfed under blankets with no will to live while nursing a broken heart over the end of her five-and-a-half-year relationship.
"I was lying in a bed in my parents' apartment under two blankets, in the same pyjamas I'd been in for three days, and I was like, 'This isn't me'. It wasn't that I was suicidal. I felt nothing. I didn't want to live," she told Cosmopolitan UK, revealing she had become addicted to her anxiety medication.
In 2018, Dunham checked into a 28-day rehab programme for prescription drug addiction after getting a hysterectomy that stemmed from her endometriosis. She also suffers from fibromyalgia and a connective-tissue disorder called Ehlers-Danlos syndrome – which means she sometimes has to rely on a walking stick to get around.
The New York native says that part of the issue between her and Antonoff was the pair met when she was only 25.
"We were both starting our careers and that was our true passion," she explained. "The love you have for someone doesn't disappear because you don't have them; it's just logistically it doesn't work anymore. I love him so much. He is a dear, dear, friend of mine."
Although she does admit it hasn't always been easy between the pair and there have been moments where she has been "catty, rude or sassy", they have been able to move forward and create a deep friendship, she said.
The Tiny Furniture director also revealed that all the major life changes had resulted in a detox from relationships, including abstaining from sex.
"I think it's been 14 months now that I've just been totally single ... I realised that until I was in a dynamic with someone who made me feel super-safe, I didn't want to do it. People right now will go, 'Oh my god, you haven't had sex in over a year', and I'm like, 'No, actually it's been the most healing thing'," she said at the time.
