A source told the mag, "They initially split about six weeks ago, but that can take a little time to extricate. But they've definitely broken up," says the source, adding, "The relationship had just run its course."
The insider added, "Jennifer is actually doing really well and working hard."
J.Lo Wows in Latex Garter Belt and Stockings at Bronx Show
News of the breakup comes amid rumors that Casper was messaging a model on Instagram.
Lopez, 44, and Smart, 27, had been together since 2011.