The 'A-Team' star - whose wife was killed in a tragic skiing accident in March 2009 - is believed to be in a relationship with UK-based public relations executive Freya St. Johnston after the pair were spotted holding hands in London earlier in the month.
The actor is now a single dad to sons Michael, 14, and Daniel, 12, while his new love interest also raises two children.
Matt Winton, Freya's ex-boyfriend, told People magazine: "She's a wonderful person and a fantastic mother. She takes life seriously in a free-spirited kind of way. They make a very nice couple."
The relationship between the pair is believed to be in its "first stages", and the 58-year-old actor's first priority is his sons.
Liam recently explained his family are "taking each day as it comes" as they continue to grieve for Natasha and carry on with their lives.
He said: "We're doing good. We are still getting extraordinary condolence letters from people. That's deeply, deeply touching."