Ben Affleck in pain as his ex-wife Jennifer Garner prepares to tie the knot?

Ben Affleck is reportedly grappling with deep sadness after learning that his ex-wife Jennifer Garner is getting ready to tie the knot with her longtime partner, John Miller.

For those unaware, Affleck and Garner wed in 2005 but decided to annul their marriage in 2015 after 10 years of togetherness, which was finalized in 2018.

The couple welcomed three children together: Violet Anne Affleck, Fin Affleck, and Samuel Garner Affleck.

An insider told Radar Online that The Accountant star is having trouble accepting the fact that Garner is preparing to move on for good by getting married to Miller, whom she calls her soulmate.

The source said, "Jennifer's been making plans for the wedding without much fanfare, and she's the happiest she's been in a long time.”

“She's been telling people that John is the person she was meant to be with. For Ben, that realization has been painful – he's always had feelings for her, and now he has to accept that she's really moved on,” the insider claimed.

The Daredevil star and Miller, CEO of Cali Group and a businessman, have been dating since 2018, and per the inner circle of Garner, this relationship became a source of her healing after her high-profile divorce from Affleck.

"John has been her anchor through everything. He's steady, thoughtful, and brings her a calm she didn't have in the past,” the source claimed.

However, despite getting separated from Garner, "Ben has always felt, deep down, that Jennifer was the one for him.”

"Now he realizes her life is moving a different way, and accepting that has been absolutely heartbreaking for him,” the insider said.