The "Underworld" star, 45, has been romantically linked to Ariana Grande's ex-fiance since February, and on Tuesday, March 19, the couple was spotted heading out for a fancy dinner with the actress' mom, Judy, and her husband, Roy Battersby, at Los Angeles hotspot Nobu.
Pete, 25, was photographed driving the group to the restaurant on the 40th anniversary of the death of Kate's dad, British TV star Richard Beckinsale.
He was just 31 when he passed away in his sleep on 19 March, 1979, and hours before the double dinner date, Kate took to Instagram to pay tribute.
"40 years is a lot of missing," she wrote beside a montage of photos of her late father. "Thank you so much to everyone who has been kind. Lots of love xx #march19."
Pete's first family outing with Kate's mom and stepdad emerged days after he brushed off concerns about the 20-year age gap between himself and his new girlfriend during a sketch on TV comedy show "Saturday Night Live", on which he is a regular.
Although he didn't mention Kate by name, he admitted he was baffled by the "crazy fascination" people had with their romance, insisting, "It doesn't really bother us, but then again I'm new to this."
Pete then began namedropping a string of male celebrities known for dating women much younger, like Leonardo DiCaprio, Michael Douglas, Bruce Willis, Harrison Ford, Alec Baldwin, and Sean Penn, to highlight the hypocrisy of the age difference gossip as older men aren't typically criticised for striking up relationships with younger women.