She is engaged to longtime boyfriend, business owner Sam Cooper, according to the U.K.'s Daily Mail.
The paper reports that Allen, 25, "burst into tears" when Cooper, 32, popped the question on Christmas Day while they were vacationing in Bali.
A rep for Allen had no comment.
The reported engagement comes on the heels of heartbreak for the couple: Allen suffered a miscarriage in the fall. The baby had been due in January.
It was the second time Allen had endured a miscarriage. In January 2008, she went through the same ordeal during her relationship with musician Ed Simons.
According to the Daily Mail, Allen and Copper, who have been dating since July 2009, drank bubbly in the bar of their hotel to celebrate their engagement and happily shared their news with other guests.