Jennifer Lopez and Casper Smart's chemistry is off the charts!

During a steamy performance of Lopez's "Dance Again" on Thursday's American Idol, the 42-year-old and her backup dancer beau, 25, got hot and heavy on live TV.

Singling out Smart toward the end of the routine, Lopez -- clad in a sparkly blue bodysuit -- recreated the sultry dance break seen in the “Dance Again” music video. (Watch a clip above)

After showing off his sexy moves, Smart came to his love's aid when she got a piece of confetti stuck in her hair. Quickly removing it as Lopez spoke with fans, Smart's gesture didn't go unnoticed by the performer.

"He's so cute!" she gushed as Smart pulled the confetti from her flowy locks and stepped back in line with the another dancers.

Together for six months, Smart and Lopez's relationship is already on the fast-track.

"She's telling friends she wants to marry Casper," one confidante recently told Us Weekly. "She's certain she wants to be with Casper forever."