Jennifer Garner ’s boyfriend John Miller is “deeply respectful” of the actress’s co-parenting relationship with her ex-husband Ben Affleck, a source tells PEOPLE exclusively. “John has embraced Jen’s family life,” the insider says. “He’s been patient, supportive and deeply respectful of her dynamic with Ben and the kids.”

Having grown up in Cambridge, Ben Affleck is well-known as a longtime Red Sox fan, and he’s clearly passing the tradition on to his kids.