Fergie and Josh Duhamel's Differences Were 'A Factor' in Split: 'This Has Been a Long Time Coming,' Says Source

Opposites attract, but Fergie and Josh Duhamel‘s differences ultimately played a role in their split.

“People close to them won’t be surprised that this ended,” a source tells PEOPLE of the couple, who, after eight years of marriage, confirmed they are breaking up on Thursday.

“A big factor is how different Fergie and Josh are,” the source adds. “In the beginning, it was what attracted them to each other and made them so fun to be around.”

Fergie is “fun and outgoing,” while Duhamel is “charming and relaxed,” explains the source. “But they come from totally different backgrounds and they wanted different things.”

In the end, their lives “were heading in two separate directions and [they] are often apart because of work,” adds the source.

While the split “has been a long time coming,” the source says, “Still, they both are obsessed with [their 4-year-old son] Axl and love being parents.”

A source close to the former Black Eyed Peas singer adds, “Josh is low-key and laid back. Fergie is more high maintenance and very focused on her career. He definitely wants more kids and has always wanted to be a family man.”

The couple confirmed their break to PEOPLE earlier in the day, saying in a joint statement, “With absolute love and respect we decided to separate as a couple earlier this year,” the couple said in a joint statement. “To give our family the best opportunity to adjust, we wanted to keep this a private matter before sharing it with the public. We are and will always be united in our support of each other and our family.”