The 30-year-old French singer confirmed she's "very in love" with Stewart in an interview with W magazine about the racy direct messages she receives on Instagram.
"I think if I was in the need of doing that right now, I would totally be able to come up with something," SoKo said of approaching partners online. "But I'm very, very, very in love and very happy in a relationship, so I don't have that urge."
"I've always been open with my sexuality, meaning I don't really care about gender," she previously explained. "Sex for so long was such a taboo thing. You couldn't be free with your sexuality and say that you like it. But it's one of the biggest joys of life."
"If you find one partner who you love having sex with, it's the best!" the star added. "This new generation is a lot more liquid with sexuality and it's really refreshing."
SoKo and Stewart were first linked in early March and were spotted holding hands in Paris on March 14. The singer revealed she once dated Stewart's ex-boyfriend Robert Pattinson in a 2015 interview with A Music Blog Yea that resurfaced this week.
"It was the best thing ever!" she said of her move to Los Angeles. "Three nights in, I went out and met a girl who was like, 'Hey, I like your music, I work for a label and we would love to sign you' ... That same night I had a blind date with Robert Pattinson!"
Stewart and Pattinson co-starred in the Twilight movies and were together several years before splitting in 2012. The 25-year-old actress and SoKo looked the happy couple as they picked up a takeout order Sunday in Los Angeles.