The Two and a Half Men star has been dating Kunis since last year (12) but has been embroiled in negotiations over a financial settlement with Moore since they split in 2011.
In October (13), the Ghost star dropped her demands for spousal support and agreed to settle for a chunk of Kutcher's wealth and a number of shares in his various technology start-up companies, paving the way for Kutcher to propose to Kunis.
A source tells Britain's The Sun newspaper, "Demi and Ashton's divorce has cast a cloud over his and Mila's relationship because it's dragged on for so long. Thankfully Demi's turned a corner. She's no longer bitter and she wants the divorce over as soon as possible so she can get on with her life too.
"They're all happy and the papers are signed and with the lawyers now, so Ashton's free to officially propose to Mila. Both of them want to marry and have children."