Actor Ashton Kutcher is reportedly engaged to his girlfriend Mila Kunis!

Actor Ashton Kutcher is reportedly engaged to his girlfriend Mila Kunis.Kunis was spotted wearing a sparkling diamond on her left ring finger while out shopping in Los Angeles on Thursday. A source tells E! News that the couple is planning to tie the knot.They started off as costars on That '70s Show, and now Ashton Kutcher and Mila Kunis are set to become husband and wife – they're engaged, a source confirms to PEOPLE. 
Wedding bells: Mila Kunis showed off her engagement ring on Thursday while shopping with her mother Elvira in Los Angeles
Following widespread speculation that the actors could soon walk down the aisle, Kunis, 30, stepped out with a diamond sparkler on her ring finger while shopping with her mother on Thursday. 
"Ashton and Mila have talked about getting married for quite a while," a business source close to Kutcher told PEOPLE in December. Adds another Kutcher pal: "They're incredibly happy together." 

Kutcher, 36, and Kunis were first rumored to be dating in April 2012, and from then on, the former costars appeared to be inseparable, enjoying some well-documented PDA and lavish vacationstogether. 

"Ashton loves to travel and so does Mila, so they have seen a lot of new places and both are charged at the idea of doing it more, even living part-time abroad," an insider says. "They seem to have a lot in common, and that helps keep a relationship strong." 

It's not the first time the couple has prepared for a wedding: In December the couple attended the marriage of Kunis's brother Michael in St. Petersburg, Fla. Later that month, the two traveled to Kutcher's home state of Iowa to spend time with his family for the holidays, then celebrated his own brother's nuptials earlier this month. 
Kutcher and Kunis met in 1998 as co-stars of the popular sitcom That '70s Show, in which they played an on-screen couple.
However, their off-screen romance did not begin until April, 2012, months after Kutcher’s 2011 separation from ex-wife Demi Moore after six years of marriage.
Kutcher and Moore's divorce was finalised last November
 The engagement news comes after it was revealed in November that Kutcher's divorce from Demi Moore had been finalized, nearly two years after the ex-couple separatedLast year, Moore sought spousal supportand legal fees from Kutcher, as the two were reportedly at odds over how to split up their estimated fortune of more than $300 million. 

Back in July, another source told PEOPLE that Kutcher was "set on proposing [to Mila]" and added that the actor "really wants to marry her and is so annoyed that there [was] still the hold-up with the divorce" from Moore.