Jennifer Lopez and Casper Smart may be calling it quits on their relationship soon. The pair have not been photographed together in about three weeks, and sources say they are on the verge of breaking up.

The couple were last seen together in Los Angeles Sept. 21. But the 44-year-old singer has long caused tongues to wag, considering her choreographer boyfriend is 18 years her junior.

Back in January, Lopez addressed their age gap, telling People, “I ask him ‘Why don’t you go find a young girlfriend and get out of here? What do you want with me?’ And you think, ‘How long is this going to be?’ You think, ‘Okay, in 10 years I’m going to be like this and you’re going to be like that’ and. … The truth is we don’t know what going to happen. We’re loving this moment right now. We make each other happy.”

But their feelings may have changed in the past eight months, though Smart and Lopez have reportedly been together since Nov. 2011.

A source tells RadarOnline, “Jennifer is pretty private about the relationship, but she’s been hinting that the spark is gone. She’s having a hard time ignoring the fact that her head has been telling her for a while that this thing with Casper isn’t forever. And now her heart’s saying the same thing.”

Meanwhile, Lopez’s ex-husband Marc Anthony, 45, has been romancing Chloe Green, 22, the daughter of Topshop founder Sir Phillip Green, since February. They recently went on vacation to Portofino, Italy, and the two looked happy and in love as they ate at a local restaurant and walked around the fishing village.