Ben Affleck and Jennifer Garner are "two different people"

A source told PEOPLE magazine: "They are really two different people. Problems got bigger in their marriage after a few years."

Meanwhile, a friend has claimed the couple split over Ben's close relationship with his ex-fiancée Jennifer Lopez.

They said: "Everyone is talking about J-Lo and Ben and saying it's inevitable they will get together again at some point. We call them the Richard Burton and Liz Taylor of Hollywood.

"They were pretty flirty at the Oscars and have stayed in touch over email. Jennifer Garner never liked it."

The pal also insisted a split has been "on the cards" for the pair - who have three children, Violet, nine, Seraphina, six, and Samuel, three, together - for a long time.

They added: "This has been on the cards for some time - it's a miracle Jen hung on so long. She has really tried but recently Ben has been back to his old self. He was drinking again while filming 'Gone Girl' and has been gambling loads too.

"Jen's fed up with him flying off to Vegas for gambling sessions and going on other solo trips, leaving her holding the family together. Their household is pretty much alcohol free so he would disappear when he wanted to indulge."