Chris Pratt & Katherine Schwarzenegger Were 'Affectionate' at Thanksgiving with Her Family: Source

Chris Pratt and Katherine Schwarzenegger celebrated their first Thanksgiving together!

A source tells PEOPLE the happy couple hung out with Maria Shriver, Katherine’s mother, as well as her brothers Patrick and Chris on Thanksgiving morning.

“Katherine’s brothers played a football game so she and Chris watched from the sideline,” the source says.

Although the couple has only been dating since June — after being set up by Shriver — the Guardians of the Galaxy star, 39, already feels at home with his 28-year-old girlfriend’s family.

“You can tell Chris knows Katherine’s family really well,” the insider says. “Chris always seems very comfortable around her family. It’s like he is part of the family.”

“Even in front of Maria, Chris and Katherine were very affectionate. They held hands, kissed and enjoyed their morning,” the source remarks, adding that “they later had Thanksgiving dinner together that Maria had organized.”

Shortly before the November holiday, the couple spent time with Katherine’s father, Arnold Schwarzenegger.

They grabbed a bite to eat at FIG restaurant at the Fairmont Miramar Hotel & Bungalows in Santa Monica, California along with the former California governor’s girlfriend Heather Milligan.

RELATED VIDEO: Chris Pratt and Katherine Schwarzenegger Are Getting ‘Serious,’ Says Source: They’re ‘Hopeful for the Future’

A different source recently told PEOPLE that while the relationship is still relatively new, an engagement may be right around the corner for the two lovebirds.

“They’re such a great fit together,” the insider said. “It’s only been a few months but Chris and Katherine are both very serious about the relationship and their friends wouldn’t be surprised if they got engaged sooner rather than later.”

The source added, “Katherine has spent time with Chris’ family and they all love her too. She fits in really well with them and vice versa.”

Pratt settled his divorce from Anna Faris earlier this month. The pair share 5-year-old son Jack.