Bill Hader and Rachel Bilson are "very happy" together

The source told E! News: "They spent Valentine's Day weekend in Orange County, California. It was a quick getaway, but time for the two of them to be together without any distractions.

"Rachel is very happy dating Bill and is excited about being with him. He treats her very well and is hilarious and fun."

The actress - who has five-year-old daughter called Briar Rose with her former partner, 'Star Wars' actor Hayden Christensen - first sparked speculation she was dating Bill back in December.

The celebrity duo were seen holding hands as they went out for coffee with members of Bill's family in his hometown of Tulsa, in Oklahoma.

Prior to that, Rachel was seen having dinner with the Hollywood actor - who has daughters Hannah, 10, Harper, seven, and Hayley, five, with his ex-wife Maggie Carey - at a restaurant in Los Angeles.

Meanwhile, Rachel previously admitted she would never date anyone who isn't fully invested in supporting her as a mother.

The actress - who played Summer Roberts on the teen drama series 'The O.C.' - recently said: "I was talking to these guys a few months back, anytime I would bring my daughter up, they would never pursue the question or ask more about her.

"It was a red flag because anyone that you're going to get involved with, if you have a kid, they have to be all about the kid."