She wasn't lying—Oliver was aware that this particular subject matter would be an incredibly important one not just for the series, but for women and uterus owners who would be watching.
"We did a lot of research on it," she explains, adding that she and the series' co-directors Leanne Welham and Lenny Abrahamson spoke to doctors and medical professionals to better understand the illness and how it could be portrayed authentically on-screen.
"I also spoke to a young woman who had endometriosis," Oliver tells us, "It was important to not just get medical accounts, but also a personal account to make it authentic and real to what it would actually be like."
After gaining this insight, Oliver knew what she needed to do.
"I think it’s really important to really let it be really painful [on screen] and not to shy away from how debilitating it can be—and to also portray the emotional effects of it. It totally effects your mood, your sense of self and your self worth."
In Conversations, Frances realises she can't run from the illness anymore, but she has a difficult time telling those closest to her about it, including her best friend and ex-lover Bobbi. Instead, she internalises it—that in itself changes their dynamic.
"There’s a feeling of weight that stays in Frances until she addresses it and until she gets any kind of diagnosis, and I think just carrying that is a huge thing in itself, even if you’re gong through lots of things in your own life.
"Endometriosis isn’t like, you get a period and you can move on, it’s in you all the time and it’s always bothering you—it’s unique for each person but that’s the case for her."
It's a strange position to be in, to play a fictional character yet shine a light on such an important issue for so many people, Oliver says.
"It’s an odd word to use but it was a privilege to get to represent [endometriosis] because hopefully it sparks a bit more of a conversation."
"That was why it was really important to me to develop [the storyline] with a lot of of conversations with people, and why we tried to make it as real as we could."
You can watch Conversations with Friends by signing up to Amazon Prime here.