However, I understand the actor bravely delivered a marry-me-or-it's-over ultimatum to Sienna during a recent romantic trip to New York.
(Ultimatum: Rhys Ifans has insisted that he and Sienna announce their engagement... or it's over)
Sienna and Rhys, left, were on a make-or-break holiday when he insisted they should announce their engagement - or end the relationship.
"Rhys is fed up with all the secrecy around their relationship and wants to make it a permanent thing," says a source.
"He has asked Sienna to marry him and it's the last time he will ask. He wants everyone to know they are officially an item."
But the champagne remains on ice. "Sienna has yet to make a decision and Rhys can't understand why," adds the source.
"Sienna's always trying to avoid the official relationship topic and is happy to keep it a low-profile affair.
('Notting Hill' actor Rhys Ivans and Sienna Miller on holiday together in Ibiza last year)
"Rhys has been happy with that but now feels they should decide whether it's going to be long-term or not. They were in Gramercy Park Hotel on Sunday, drinking cognacs with soda.
"Sienna paid - it was as if she had some making up to do."
A spokesperson for Sienna said the pair had both been in New York for work reasons.
