During his performance of the song “Twin Flame” at Sunday’s 2022 Billboard Music Awards, Kelly said “I wrote this song for my wife.”
The awards show happened a day before Fox’s birthday and Kelly said, “Happy birthday my love” as he performed.
He also said: “This is for our unborn child.”
Neither has announced either a wedding or a pregnancy, and Kelly has referred to Fox as his “wife” before.
He has a daughter, Casie, 12, from a previous relationship, while Fox shares three sons, Noah, 9, Bodhi, 8, and Journey, 5, with her former husband, actor Brian Austin Green.
CNN has reached out to reps for Kelly for comment.