Justin Bieber -- I'll Make Love to ... A Newly-Engaged Couple (VIDEO)

Justin Bieber is apparently taking his rendition of "I'll Make Love to You" on tour ... because he performed it again Thursday night, but this time it was just for a freshly-engaged couple.

Bieber was leaving The Grove in Hollywood Thursday night when he came across the couple who had just gotten engaged. The guy asked Justin to sing to his fiancee, and Biebs obliged ... but made the guy sing the hook.