Ashton Kutcher and Mila Kunis ''share the responsibilities'' of parenting.

The 41-year-old actor and the 'Family Guy' star have been married since July 2015 and have two children, daughter Wyatt, four, and son Dimitri, two, together.

And sources have now said the pair lead a ''very fulfilling life'' together, as they equally share the responsibilities of parenting their brood, and work hard to keep each other ''grounded''.

One insider told People magazine: ''Mila and Ashton have a very fulfilling life and love sharing the responsibilities of being parents. Their children keep them busy and cause stress but they are both so well grounded in their relationship, it has done nothing but bring them closer together. They are very happy.''

The couple first met when they starred together on 'That 70s Show' when Mila, now 36, had her first kiss at 14 during a scene with 19-year-old Ashton.

Although the pair would go on to date other people - with Mila dating Macaulay Culkin, and Ashton marrying Demi Moore - they eventually reconnected and began a romantic relationship several years later.

Speaking about their romance in July last year, Mila said: ''I did a movie called 'Friends With Benefits'. He did a movie that was very similar called 'No Strings Attached'. We lived out movies out. We were just like, let's just hook up. Let's have fun. We're both single. We both trust each other. Everything's great.''

But before long, the pair had become too attached to keep things casual.

She added: ''I felt like I got punched in the gut, literally overnight. I was like, you know what, I actually care about you. I don't want to mess anything up so I'm just going to walk away before it becomes too much.''