While fans mourned the end of Ben Affleck and Jennifer Garner's marriage, few in the former couple's inner circle were surprised to hear the news.
"They have both been very open about their marriage struggles," one friend tells PEOPLE in this week's cover story. This split, says another pal, "was inevitable. If there's any surprise, it's how long it took to happen."
So what was the breaking point? According to a longtime friend of the actress, Affleck recently came to Garner "and told her he had not been committed to the marriage within the past few years," her friend says. "Jen is a fighter. She would not give up unless there was a good reason."
Several sources close to Garner also say that allegations of infidelity (which Affleck vehemently denies) and other troubling behavior, including drinking and gambling, took their toll on the marriage. "She loved Ben," says another close friend. "But there comes a time when you have to say enough is enough and take care of yourself."
Other sources insist the split was mutual. "Saying he's a bad father and a husband is an easy story, and everyone has wanted to clock him as a womanizer and gambler," says a source close to both. "He couldn't deal with her expectations. When you're told you're not good enough, you start to believe it."
For now, the two have work commitments to keep them busy: Affleck plans to attend Comic-Con International this weekend in San Diego to promote Batman v Superman: Dawn of Justice, while Garner is in Atlanta to begin production on her next film, Miracles from Heaven.
Friends agree the two will remain united when it comes to co-parenting their three kids, Violet, 9, Seraphina, 6, and Sam, 3, who are currently with Garner.
"It's nice to at least try to move in a positive direction with your life," says the source close to the couple. "It's not happy, it's not easy, but it's nice to look forward."
Reporting by ELIZABETH LEONARD and LIZ MCNEIL
For more on why Affleck and Garner decided to end their marriage, pick up this week's issue of PEOPLE on newsstands Friday