Jennifer Lopez Spends Time with Ben Affleck at His L.A. Home Ahead of His Birthday (Exclusive Source)

Jennifer Lopez visited Ben Affleck at his home over the weekend after spending much of the summer apart.

A source tells PEOPLE that the Atlas actress, 55, stopped by Affleck's rental home in Brentwood on Sunday, Aug. 11, while he was there. Earlier in the day, she accompanied his son Samuel, 12, to the mall.

Lopez, who has 16-year-old twins Max and Emme with ex-husband Marc Anthony, is eager to spend time with Affleck's kids before school begins, the source says. Affleck and ex-wife Jennifer Garner share Violet, 18, Seraphina, 15, and Samuel.

"Just because she's not with Ben doesn't mean that she doesn't care about his kids," says the source.

"She always cared about them. She spent months looking for the perfect house for their blended family last year. Now when she's back in L.A. she wants to spend quality time with them before school resumes and Violet is off to college."

A source previously told PEOPLE on Aug. 6 that Lopez and Affleck — whose 52nd birthday is this Thursday, Aug. 15 — hadn't seen each other "in weeks." Added that source, "They’re moving on separately. Jennifer is trying to find a new home to start fresh."

Days later, another insider said Affleck is "doing well" and "thrives when he’s busy, and he’s been working nonstop."

"The kids are still off from school. He spends a lot of time with them too," said the insider, adding, "It hasn’t been the easiest summer for him either. He’s just trying to stay focused and make every day as good as possible."

Affleck and Lopez, whose second wedding anniversary came and went in July with no fanfare, have not publicly commented on the state of their marriage. Signs of trouble in their relationship became apparent in May, as sources said the two were living separately.

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One source said that Lopez is "having a good summer," even "considering everything that's going on."

Added that source, "She's been off and able to focus on what's next. She’s enjoyed spending time with her kids, family and friends. She always has good attitude even when things are not perfect."

Lopez, who canceled her summer concert tour to spend time with family, next stars in the movie Unstoppable, which is produced by Affleck's company and is set to premiere at the Toronto International Film Festival in September.

Affleck wrapped filming The Accountant 2, a sequel to his 2016 action film, and he'll be teaming up with Matt Damon to costar in the Netflix crime thriller RIP.