Sienna Miller and  Rhys Ifans were never the most likely celebrity pairing.

Now just months after rumours of a summer wedding it seems their relationship may be on shaky ground.

Friends have said Sienna is struggling to cope with Rhys' possessiveness and his behaviour reminds her of 'controlling' ex-boyfriend Jude Law.

Rocky times: Sienna Miller and boyfriend Rhys Ifans are reported to be having relationship troubles

Sienna accused Rhys of being like her ex-boyfriend Jude Law

A friend told Closer magazine: "Rhys gets very jealous - he hates her socialising with other men and always wants to know where she is and who she's with. During a row she yelled at him: 'It's just like being with Jude."

"Rhys freaked out, because he prides himself on being the laid-back opposite of Jude. But he just gets worked up seeing men admiring his girlfriend and trying to hit on her," the source continued.

According to Closer, the tensions have been worsened by the pair being split by work commitments. Sienna has been filming GI Joe in America while Rhys has been working in the UK.

"They had a huge bust up recently," the friend told the publication.

"Sienna promised to spend a week with Rhys. He arranged his filming schedule, but at the last minute she canceled her trip, saying she had to work. Rhys hit the roof when he called her and found out she was partying in LA."

"It's awful but everyone who knows them can just see it coming a mile off, a source told Grazia magazine.

The confidant added: "Rhys still seems madly in love with her but everyone's speculating Sienna has grown out of the relationship."

"It's almost painful to see them gone from being this 24/7 love-fest to him looking as if he's struggling to keep her attention. It's so sad."