Are Ben Affleck & Jennifer Lopez Getting Serious?

Bennifer is back on, but just how serious are Ben Affleck and Jennifer Lopez?

A source close to Lopez tells People, "This is not a casual relationship," adding, "They are taking it seriously and want it to be long-lasting."

The update comes after Jennifer reportedly spent the weekend with Ben in L.A. The insider says she was in town for business, but also wanted to see her man.

The source explained, "They will continue to travel back and forth between Los Angeles and Miami. They are very happy together."

Just last week Affleck was spotted in Miami, and the couple was spotted kissing at Anatomy Miami Beach.

"They were holding hands, hugging, kissing,” a source told People. “They weren't trying to hide the fact that they were together. They are very much into each other and being together."

The insider went on, "Truthfully, they are really nice people. No one stands around the gym saying, 'Don't approach them.' No one bothers them; everyone is respectful. Everyone loves her. All the women are checking her out and her routine because she looks so amazing and is so strong."

Fans started speculating about another round of “Bennifer” when they were photographed outside her home in April. The stars also participated in the Vax Live concert last month, although they did not appear together at the fundraiser.

Soon after, however, Ben and Jennifer were spotted together near a Big Sky resort in Montana. Ben has a home in the area, and the exes were seen riding together, with Ben behind the wheel and J.Lo in the passenger seat.

Lopez and Affleck began dating in 2002, and got engaged a few months later. They postponed their 2003 wedding, and ultimately split in January 2004.