'Two and a Half Man' actor Ashton Kutcher is rumored to tie the knot with America's Esquire magazine's voted 'Sexiest Woman Alive' Mila Kunis as soon as his divorce from Demi Moore is formally approved - the 35-year-old heartthrob is head over heels serious with the 30-year-old actress, a source said.

Mila and Ashton first met on the set of the sensational tv series 'That 70s's Show' where the former played Jackie and the latter, Michael. Counting the years where they have known each other from 1998 to present, it would roughly be 16 years, and despite this long period the two hadn't taken their relationship to the canoodling stage until early last year.

"They plan to get engaged soon. Being with Mila brought Ashton back to who he really is," a US Weekly magazine inside source said, referencing to the actor's previous marriage with now 50-year-old Demi Moore.

"He's not playing the field, he's focused on enjoying Mila and the happiness she brings," the same source said, adding that Mila doesn't get easily jealous like Demi used to. "He calls her because he wants to and when they're apart they talk constantly.

According to the source, Ashton audaciously regards Mila as "THE ONE" in striking capital letters; thus, his penchant for putting a ring on her finger doesn't come as a surprise to his friends and family.

Many people think the Mila is the perfect match for Ashton, since the actress - aside from being younger than he is - is an obviously sassy yet quite humble star. In her recently received magazine plaudit for being sexy, she commented: "I don't know how to answer that question without sounding like an asshole. Either way, I am damned. It's a great honor, I think it's nice."

Ashton Kutcher and Demi Moore: On Calling It Quits

While the world was shocked after Ashton Kutcher and Demi Moore got married in September 2005, their "roller coaster" relationship and impending divorce didn't come as a surprise.

Sources say that the 15-year age gap between the couple was the root cause of their problems from the very beginning.

While Ashton was trying his best to keep things subtle, his somehow ageless wife had always been very suspicious of his exploits and movie-related rendezvous, gradually breaking the trust that they have established through matrimony.

Today, the couple are enjoying separate paths, and are most likely going to maintain their relationship that way. And since the speculations on Ashton's plan of marrying Mila Kunis were proven true, the couple's married life is doomed to meet its end.

Ashton Kutcher is currently busy with the smash hit series 'Two and a Half man,' taking over Charlie Sheen's lead role. He has starred in various big-screen projects such as 'Valentine's Day' and 'New Year's Eve,' and is already set for another major project December this year.

As for Demi, she has recently worked in 'Another Happy Day,' an Ellen Barkin-starring drama, the critically-acclaimed 'Margin Call,' and a comedy entitled 'LOL' where she co-starred with famous pop icon Miley Cyrus and 'Twilight' discovery Ashley Greene.