Kutcher, 41, and Kunis, who celebrated her birthday on Wednesday, married back in July 2015, with Kunis giving birth to their daughter a year later. The couple now share two children: daughter Wyatt, 4, and son Dimitri, 2.
Four years later, the two are going strong as the dynamics of their relationship change with their kids becoming their priority.
“Mila and Ashton have a very fulfilling life and love sharing the responsibilities of being parents,” an entertainment source tells PEOPLE. “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 adorable couple was destined to be together since Kutcher was Kunis’ first kiss on That ’70s Show. Kunis was only 14 when she was cast, while Kutcher was 19.
Although the two would go on to date other people — Kunis would have a lengthy relationship with Home Alone star Macaulay Culkin, while Kutcher went on to marry Demi Moore — they reconnected after time apart.
Kunis opened up about how their romantic relationship began in July, 2018 while on the WTF with Marc Maron podcast.
“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,” the actress said. “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.”
What began as a casual relationship inevitably escalated to something more serious. After attempting casual hookups, Kunis took charge when she realized her feelings for Kutcher after he told her about someone he was dating.
“I felt like I got punched in the gut, literally overnight,” she told Maron. “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.”
As for whether the two will ever act together again, Kunis immediately shot the idea down during an interview in 2018 on Sunday TODAY with Willie Geist.
“Not going to happen,” she said. “I can’t look at him and not be like, ‘What are you doing?’ …no, it’s weird.”