Thirty-nine-year-old Spears announced the news in a video on her Instagram account, where she posed alongside Asghari, 27, and held a four-carat diamond up to the camera. Thousands flocked to congratulate the couple, who have been dating for almost five years. The ring, already branded “The Britney,” is engraved with the word “Lioness” — Asghari’s nickname for the star.