Garth Brooks' daughter Allie had one heck of a 21st birthday: She sang backup for her dad, got a birthday serenade from him and the crowd ... and got engaged backstage!

During Garth Brooks' Friday night (July 28) World Tour stop at the Forum in Los Angeles, Allie Brooks' boyfriend, Jonathan Roberts, surprised her with a marriage proposal (while, quite adorably, her father was onstage singing his song "She's Every Woman"). Readers can press play below to watch the special moment.

According to his Facebook page, Roberts studied health at Middle Tennessee State University and teaches physical education at George Whitten Elementary School in Hendersonville, Tenn. Allie Brooks is Garth Brooks' youngest daughter with his ex-wife Sandy; she has two older sisters, Taylor and August.

While onstage with her father, Allie Brooks was also treated to a pretty epic rendition of "Happy Birthday" while he was introducing his band. After telling the crowd a little bit about his daughter -- she "can play a mean acoustic guitar" and is "a great songwriter, great singer," he says -- Garth Brooks lets fans know that it's her 21st birthday, cues up his band and gets the crowd singing along. Press play on the video below to watch the special moment.

Brooks and wife Trisha Yearwood have been out on the road for his World Tour since September of 2014. In addition to their show at the Form on July 28, they performed at the venue on July 21, 22 and 29.

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