Abbie Cornish and Ryan Phillippe are back on

Dec 6, 2007, 13:30 GMT

10/01/2007 - Abbie Cornish - Elizabeth The Golden Age Los Angeles Premiere - Gibson Amphitheate, Universal City Walk - Universal City, CA, USA © Glenn Harris / PR Photos

Ryan Phillippe has reportedly introduced his children to his new girlfriend.

The 'Crash' star was seen Christmas shopping with Abbie Cornish - the woman he was accused of cheating on ex-wife Reese Witherspoon with - and his two kids with Reese, Ava, eight, and four-year-old Deacon.

An onlooker told Us Weekly magazine: "Ava seemed very comfortable with Abbie. Ava picked a wreath and Abbie put it around her head as a joke. They were both laughing."

Sources claim Ryan and Abbie - who have previously denied claims of an affair - are smitten with each other.

One said: "They have a ton of chemistry. Abbie is a free spirit. She indulges a side of Ryan that he's kept under wraps for years."

Ryan split from Reese in October 2006 over claims he had been seeing Abbie while they were still married.

A source said at the time: "Ryan admitted it was true and said, 'We need to just end this.' Reese literally had no choice."

Ryan, 32, met Abbie on the Texas set of their independent film 'Stop Loss' and it has been reported the couple were extremely open about their relationship during filming.

The source said: "Ryan did not go out of his way to hide the fact that he was having a fling with his co-star Abbie. Besides the fact they were spotted making out in a sushi restaurant together, she was spotted many times leaving his loft apartment."

Reese and Ryan met at Reese's 21st birthday party and starred as lovers in cult teen movie 'Cruel Intentions'.

(C) BANG Media International