Maybe translating the entire quote will make it clearer:

"I'm not sure whether the manga I'm writing is what people call 'yuri.' It's more like 'love between women'; I feel a fascination toward that theme. There was a time when I myself struggled [she uses "nayamu" here] with my sexuality, so it makes me very happy to see people with different sexualities, backgrounds, lives, and occupations read the stories and characters born from that time [in my life]. Please continue to kindly watch over Mitsuki and Aya."

If this story and these characters are inspired by the period in Sumiko's life when she was struggling with her own sexuality, I think it's safe to say they're not just going to be straight, platonic friends.

Or she realized she was straight but still has a fetish for lesbian relationships.