Sienna Miller and Tom Sturridge ''stayed together'' for their daughter.

It was revealed last week that the couple had called time on their relationship, just weeks after they were pictured enjoying a holiday on the Mediterranean islands of Ibiza and Formentera, but insiders claim they had actually separated long before their sunshine break and had been putting on a united front for the sake of three-year-old Marlowe.

A source said: ''It seems they were staying together for Marlowe.

''They'd actually already split up when they went to Formentera.

''Recently they've been going to events together but they weren't 'together together'.

''They seemed to be trying to keep it up for Marlowe but it looks like they had finally come to the conclusion that things are not working for now.

''Sienna values honesty and it seems neither of them wanted to live a lie as their daughter grows older, so they called off their engagement.''

However, the 'American Sniper' actress - who previously had an on/off relationship with Jude Law and dated married father-of-four Balthazar Getty in 2008 - is said to be relieved she and the 29-year-old actor have been able to end their relationship without ''drama''.

A source told Grazia magazine: ''It's been difficult and not a decision they've come to in a hurry, but it seems that Sienna is actually quite relieved they've come to an agreement to call it a day without any drama.''