Mum-of-two Jennifer, 44, has reportedly called it quits with the 27-year-old dancer after more than two years of dating.
Rumours of a break-up have been intensifying in recent days, with accusations in the US that Casper had been getting cosy with a transgender model he'd met online.
That has not been confirmed.
According to today's reports, J.Lo and Casper actually split a while ago, but the news is only coming out now.
A source told Us Weekly it had been an "amicable process" and they'd remained friends, citing their busy careers and being in different cities for work as a problem.
That insider said J.Lo didn't believe the claims about Casper and the model, so that wasn't an issue. It was more about them being apart so much as she focused on her career and he continued to build his profile.
Meanwhile, a separate source confirmed with Entertainment Tonight the break-up was a few weeks ago.
Another insider told People that "the relationship had run its course" and Jennifer is doing fine, focusing on her work and children.
She has five-year-old twins, Emme and Max, from her marriage to ex-husband Marc Anthony.
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Celebrity splits of 2014 in pictures:
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