Ben Affleck Is "Getting to Know" Jennifer Lopez's Twins Emme and Max

• Ben Affleck is already bonding with Jennifer Lopez's kids, Emme and Max.
• An insider told People, "They are slowly getting to know Ben. Everything seems to be running smoothly."
• "It's very obvious that Jennifer is serious about Ben. She hasn't looked this happy for a long time," the source continued.

This is extremely sweet: Ben Affleck is reportedly bonding with Jennifer Lopez's kids, Emme and Max, after reuniting with his former fiancée. The twins, 13, "are slowly getting to know Ben," a source told People. What's more, Emme and Max are "onboard with starting fresh in Los Angeles," the insider added, after recent reports that Lopez was looking at schools and properties in the area.

"Everything seems to be running smoothly," the source continued. "It's very obvious that Jennifer is serious about Ben. She hasn't looked this happy for a long time."

On Sunday, Affleck joined Lopez for a family dinner at Nobu in Malibu, celebrating the birthday of J.Lo's younger sister Lynda Lopez. Emme and Max were also present—and onlookers said the group had a pretty lovely evening. "They enjoyed a Sunday family dinner together," another insider told People, adding, "everyone seemed great and had fun."

"Ben and [Lopez's] kids seemed comfortable together," the source shared. "The kids kept chatting with Ben. Ben seemed great. He was smiling and laughing. They ordered a lot of food to share." What's more, "Jen and Ben sat next to each other and were very affectionate," the insider added, observing that "they held hands under the table."

Last week, Us Weekly reported that Lopez was planning a move from Miami to Los Angeles, where Affleck lives. According to the magazine, J.Lo's already looked at houses in the areas, as well as schools for Emme and Max. "Jennifer is looking forward to coming back to L.A. for a new start," a source said.