The news follows reports that they were on the rocks as the couple have recently hit the headlines amid allegations that Casper has been sending messages and photos to a transsexual bikini model.
A source told People magazine: "They initially split about six weeks ago, but that can take a little time to extricate. But they've definitely broken up."
The source added: "The relationship had just run its course."
Jennifer Lopez and Casper Smart
People had previously reported that the 44-year-old American Idol judge and Casper, 27, had "hit a rough patch" a few months ago.
"Now, all this stuff comes out... They're still together, technically, but no idea for how long." said the source on Thursday.
Jennifer, who is the mother to six-year-old twins Max and Esme from her previous marriage to Marc Anthony, is reportedly "doing really well and working hard."
Promoting her tenth album, she said that her divorce from Marc Anthony marked a real turning point in her life.
"My topic is love. It always has been," the singer said.
"It's my motivation. It's what I think about. That's who I am at the essence. But what I thought about love for my first nine albums is very different from what I think about it now, after everything I've been through", she added.
After three divorces, Jennifer had confessed she was in no rush to walk down the aisle again, and when her and Caspar first began to date in 2011 it was "not meant to turn into anything more."
"In the past, love for me has always meant forever, and sure you nurse those fantasies, but I don't try to force it anymore," she said in an interview with InStyle.
"I hung on to my fairy tale ideals for a long time. But where I am now, what I've been through, there are no rules. There are lots of ways it can turn out instead of just one."