Radar Online also ran a report suggesting Garner, 43, has reached breaking point after years of problems in the marriage.
An insider said: "Often, when Ben and Jen have a problem, they just agree to ride it out and be miserable together until they can get some time apart."
They added: "Jennifer has close friends who think that she and Ben are a horrible fit, despite how much he loves being a father to those kids."
Another insider told the publication: "Jen has actually been preparing herself emotionally for this divorce for some time.
"She sees a therapist to learn how to cope with the divorce, and how to deal with the kids after they split. She'll take custody of them."
The website also said Affleck and Garner have been spending more and more time apart with the Gone Girl star spotted playing high-stakes poker for several hours in Las Vegas on May 3.
He was again spotted gambling in Sin City in the early hours of May 14 while his wife was in New York, suggesting that the actor had left the children with a babysitter.
And on Garner's birthday on April 17, Affleck was reportedly seen on a solo trip in Canada without his wedding ring.
"He's told Jen that he wants the official statement to come out before their ten-year wedding anniversary on June 29," an insider told Radar.
The actress recently said that her marriage to the Argo star requires a lot of "patience" as she revealed to Yahoo! Parenting last week.
"You just go on a ride together because you don't know who you're going to be when you first have a baby and you don't know who [your partner] is going to be," she told them.
She continued: "You have to just hang in there while you figure it out - and have a lot of patience for each other."
The couple sparked a friendship on the set of 2001 flick Pearl Harbor and went on to star alongside each other in the 2003 film Daredevil.
Years later, Affleck admits he fell in love with Garner on the set of Daredevil - which was filmed over summer 2002 - in an interview Playboy: "That's where I found my wife. We met on Pearl Harbor, which people hate, but we fell in love on Daredevil."
They started dating in late 2004 before getting engaged in April 2005, marrying two months later in a private ceremony in the Turks and Caicos while Jennifer was pregnant with their daughter Violet.
Affleck previously dated singer/actress Jennifer Lopez from June 2002 to January 2004, during which time they became engaged, but called off their planned September 2003 wedding at the last minute.
Meanwhile, Garner was previously married to Grey's Anatomy and Felicity actor Scott Foley from 2000 until 2003.
In a 2013 interview with Allure magazine, she said of her first marriage: "We didn't have a shot. He's a really good guy, and we just imploded.
"We were full-on grown-ups, but looking back I'm aware we did not know what hit us."
Dailymail.com has contacted Ben and Jennifer's rep for comment.
- The Daily Mail
