New York: Actress Sienna Miller is to marry boyfriend Rhys Ifans after his third proposal and plans to keep it a low-key affair.

Miller, who has previously called Ifans her soul mate, recently said, "I am in love - Rhys and I are the best of mates and life is going great."

"The Factory Girl" star is said to be planning a summer wedding with the 39-year-old actor, who first asked for Miller's hand in marriage in August by sending her a cryptic message in Welsh, his first language, which read: "Marry the misfit."

He proposed for a second time in December at her 26th birthday party by hiding an engagement ring in a pile of gifts.

But it proved to be third time lucky for him after Miller accepted his proposal earlier this month, imdb.com reports.

And the couple is reportedly keen to keep their forthcoming nuptials low-key. A source said, "Rhys has admitted he and Sienna are getting married. Everything is supposed to be hush-hush, but Rhys is over the moon and finding it hard to keep quiet. He can't believe she finally said yes.

"Although Sienna and Rhys have a lot of famous friends, they will keep it low-key. They won't be signing up to some magazine deal."