The Oscar-winning actor announced his separation from wife Robin Wright Penn recently.
He then turned up with Nemcova for Sir Elton John's post-Academy Award night bash.
However, the status of the relationship was called into question by the fact that though Penn and Nemcova sat together all night long, the lady in question spent most of her evening on her Blackberry.
'Petra spent much of the night with her face downwards, busy on her BlackBerry. Actor Christian Slater stopped by the table but Petra was oblivious,' The Sun quoted a party guest, as saying.
'Sean had to tell her to introduce herself. She did but then quickly turned her attention back to her BlackBerry. She did this with other guests who chatted to Sean.'
Text: ANI | Photograph: Getty Images