"Jason adores [Britney's] kids; he loves them," a source tells PEOPLE. "He was like their 'other dad,' so he's not just going to walk away from their lives. He'll be involved as much as makes sense."
As for Spears's two boys, Preston, 7, and Jayden, 6, the source says they "are doing great and [their father] Kevin [Federline] is actually a huge help and is a wonderful person in their lives."
Despite reports that the former X Factor judge's desire to have more kids was a reason for the split, the insider says, "Jason is genuinely open to kids of his own."
But the source adds, "There were so many issues in their relationship that Jason really wanted those worked out before they could ever move forward with a wedding or more kids together."
In the end, Spears, 31, and Trawick, 41, do "love each other," says the source. However, "there were some major challenges and hurdles and constant work that needed to be done. ... It just wasn't working and things weren't going to change, so it was time to let go."