The dancer/choreographer, whose 2½-year relationship with Jennifer Lopez, 44, recently ended, has been packing up his belongings from Lopez's Los Angeles home.
"He is upset about the split," a source says. "He really wanted to stay with Jennifer. He loves her and her kids."
Smart, 27, had been in Mexico premiering a short film but returned to L.A. on Friday to begin collecting his things.
One perk that comes with breaking up with one of Hollywood’s hottest stars? "He gets to keep all the gifts that Jennifer bought him, including the customized truck that she gave him for his 25th birthday," the source says.
Although love might not cost a thing, the source says, "Jennifer has always been very generous and Casper has bags of things to move out."
He did manage to squeeze in a little fun, attending a concert by his friend, reggaeton musician Yandel, and – hey, why not, he's single – posting impressive shirtless photos of himself on Instagram.
Meanwhile, Lopez was in New York City promoting her new album, A.K.A..
She was all smiles Saturday at a listening party at the Beats by Dr. Dre store, where, according to attendee Kat Sanchez, she was "in great spirits" and later told the crowd, "There has never been a more special project, special time in my life than this one."
Reporting by MELODY CHIU