The 39-year-old Guardians of the Galaxy and Jurassic World star and the daughter of Maria Shriver and Arnold Schwarzenegger began dating this summer. Last month, they spent Thanksgiving with Katherine's mom and siblings and also went on a double date with Katherine's dad and his girlfriend, Heather Milligan. Katherine turned 29 this week and had a "low key" birthday celebration with Chris and her family, a source told E! News.
"Everyone met up at Maria Shriver's house in Brentwood for a dinner party and birthday cake," the source said. "Katherine had a few friends over along with her siblings and Chris. They are all very close and tight knit."
"Chris is treated like one of the family and they all love being together," the source said. "He gets along with her brothers and of course her mom. They all really think the world of him. He makes Katherine incredibly happy and everyone is excited about them and their future as a couple."