Former boyfriend upset about her relationship with his Brothers & Sisters co-star Balthazar Getty

Sienna Miller’s new man Balthazar Getty is rumoured to be very unpopular on the set of Brothers & Sisters.

He stars in the hit US show with 26-year-old Sienna’s ex Matthew Rhys, 33 – who’s said to be distraught she’s dating the oil heir.

The actress was snapped kissing married Balthazar, 33, while on holiday in the Italian Riviera.

‘Matthew feels betrayed by both Sienna and Balthazar,’ a source tells The Sun. ‘It’s an edgy situation on set. Matt has been consoled by other starts including Sally Field, who’s been like a rock.’

Balthazar yesterday released a statement confirming he’s split with wife Rosetta. The couple have 4 children.