Hilary Duff reportedly felt her estranged husband "didn't put enough" into their marriage.
The 26-year-old star confirmed her three-year marriage to former ice hockey player Mike Comrie was over at the end of last week.
The pair have 21-month-old son Luca together and insist their break-up is amicable, but it's been claimed Hilary didn't feel her partner's heart was in it anymore.
"She felt he didn't put enough effort into the relationship," a source told Us Weekly magazine.
When they confirmed their separation is was reported the pair had tried hard to save their marriage, even going to couples' therapy. It's now been claimed they were actually in counselling for 18 months, but towards the end Hilary feared Mike wasn't trying hard enough.
"Recently he wasn't doing any of the things they'd worked on," the insider claimed.
One of the problems is thought to be that the former sportsman struggled to adjust when an injury meant he needed to retire from the game. Eventually the former couple realized they couldn't save their union and would be better off as friends.
"The spark was no longer there," another insider claimed.
Although they are no longer romantically involved, Hilary and Mike, 33, are still close. They were seen enjoying a meal out together just two days after they released the statement confirming their separation.
They were also with each other on the day the news went public, with Hilary telling fans how much their well wishes meant to them both.
"Mike and I are sitting here," she tweeted on Friday. "We are so appreciative for all of your kindness & well wishes. Not an easy day but we're getting thru it together (sic)."