In the wide-ranging interview, Stewart, 29, explained why she and Pattinson chose to never speak publicly about their relationship.
"When me and Rob were together, we did not have an example to go by," she recalled. "So much was taken from us that, in trying to control one aspect, we were just like, 'No, we will never talk about it. Never. Because it's ours.'"
Stewart and Pattison, 33, famously started dating after co-starring together in 2008's "Twilight." The couple went on to star in four sequels in the franchise, the last being released in 2012.
The pair first broke up in 2012 after Stewart was photographed kissing her "Snow White and the Huntsman" director Rupert Sanders, who was married at the time. Although Stewart and Pattinson reconciled, they ended things for good in 2013.
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Stewart has gone on to have relationships with women, including model Stella Maxwell. (She has most recently been romantically linked to screenwriter Dylan Meyer, according to E! Online.)
Despite stating she is "like, so gay" when she hosted "Saturday Night Live" back in 2017, Stewart doesn't identify her sexuality or use labels.
"I think I just wanted to enjoy my life. And that took precedence over protecting my life, because in protecting it, I was ruining it," she added to Harper's Bazaar. "Like what, you can't go outside with who you're with? You can't talk about it in an interview?"
Stewart continued, "I was informed by an old school mentality, which is --– you want to preserve your career and your success and your productivity, and there are people in the world who don't like you, and they don't like that you date girls, and they don't like that you don't identify as a quote unquote 'lesbian,' but you also don't identify as a quote unquote 'heterosexual.' And people like to know stuff, so what the f--k are you?"