• Jennifer Lopez and Ben Affleck attended her sister's 50th birthday together Sunday in Malibu, California, a report says
  • The two were photographed kissing during the celebration held at the restaurant Nobu
  • Lopez's children were reportedly also present during the celebration

Jennifer Lopez and Ben Affleck made it clear that they are officially back on after being spotted locking lips publicly for the first time since rekindling their romance last month.

Affleck, 48, and Lopez, 51, were photographed kissing Sunday while dining at the sushi restaurant Nobu in Malibu, California, with her extended family.

In the photos obtained by Page Six, the singer can be seen pulling Affleck in close to his shoulder, and he moved in for a kiss. She also caressed his face as they looked into each other's eyes in the intimate moment. One snap showed the "Justice League" star leaning in closer to Lopez and appearing to whisper something into her ear at one point.

Lopez and Affleck were at the restaurant to celebrate the 50th birthday of her sister, Lynda Lopez, and they were surrounded by the singer's family members, according to the outlet.

An unnamed source told People that it was a "small birthday celebration" and "everyone seemed great and had fun."

"They enjoyed a Sunday family dinner together," the insider added. "Jen and Ben sat next to each other and were very affectionate. They held hands under the table."

A video from the celebration obtained by Page Six revealed that Lopez's 13-year-old twins, Emme and Maximilian, whom she shares with ex-husband Marc Anthony, were also present during the celebration. The twins were seen approaching their mom and Affleck to show them something on a smartphone.

"Ben and her kids seemed comfortable together," the source told People. "The kids kept chatting with Ben. Ben seemed great. He was smiling and laughing. They ordered a lot of food to share. Ben had a Diet Coke."

While Lopez and Affleck have not publicly spoken about their rekindled romance, Us Weekly reported in May, citing an unnamed source, that they "are full-on dating and very happy together" 17 years after they ended their engagement in 2004. Since then, the two have been spotted multiple times together.

The pair reunited in Los Angeles Friday after being apart for a few days, People reported. Affleck was in Las Vegas to direct an undisclosed project, in which Lopez's mom, Guadalupe Rodriguez, is reportedly set to make a cameo. The "Let's Get Loud" singer's boyfriend and mom were seen bonding at the Wynn resort and casino Wednesday.

As her relationship with the actor heats up, Lopez has reportedly decided to leave Miami and move to Los Angeles with her kids to be with Affleck. "She is excited about a fresh start and pursuing things with Ben. They will be at their L.A. home soon," an unnamed source told E! News.

Ben Affleck and Jennifer Lopez
BEVERLY HILLS, CA - OCTOBER 20: Actress/singer Jennifer Lopez and actor Ben Affleck hold hands while filming her new music video at Barefoot restaurant on October 20, 2002 in Beverly Hills, California. Ben-Ari Finegold/Getty Images