Conceding they had been through more than a few rough patches, she said, “We’ve broken up a couple of times and gotten back together, and this time I was like, "Finally, I can feel again.’ ”
Stewart and Cargile, who were spotted holding hands as they returned from the Cannes Film Festival in May, have been dating on-and-off for more than a year.
Los Angeles-born Stewart also said she felt more open about her relationship now that she is dating a female.
"When I was dating a guy I was hiding everything that I did because everything personal felt like it was immediately trivialized, so I didn't like it,” she said. "But then it changed when I started dating a girl."
“I was like, 'Actually, to hide this provides the implication that I'm not down with it or I'm ashamed of it, so I had to alter how I approached being in public. It opened my life up and I'm so much happier."
Stewart split from her Speak co-star Michael Angarano in 2009 following a three-year romance. Shortly after, Stewart began dating her Twilight co-star Robert Pattinson. They split in 2013. While dating Pattinson, Stewart had an affair with her Snow White and the Huntsman director Rupert Sanders.
In May, the actress told Variety that she chooses to remain vague about her sexual orientation.
"Me not defining it right now is the whole basis of what I'm about," she said. "If you don't get it, I don't have time for you."