Jennifer Garner's Boyfriend John Miller 'Has Shown Incredible Patience' Toward Her Ex Ben Affleck: Source

John Miller must really love Jennifer Garner!

According to an insider, the boyfriend of the famous actress, 46, has been working with the mother-of-three to support her ex Ben Affleck amid his divorce battle with Jennifer Lopez.

“John has shown incredible patience and that he’s really endeared him to Jennifer,” the insider shared of the CEO, who was first romantically linked to the 13 Going on 30 star, 52, in 2018.

While the couple was hoping to tie the knot soon, Affleck’s split from Lopez may have foiled their timeline.

“[Affleck] got a key to come and go as he pleases, and he’s been spending a ton of time at [Garner’s] place, coming over for dinners and hanging with the kids,” another source revealed of the Good Will Hunting alum, who shares Violet, 18, Fin, 15, and Samuel, 12, with Garner.

“It’s great for his state of mind and the kids love having him around,” they explained, noting it’s “why Jen’s open to the idea of having him move back in.”

The first insider shared that though Miller tries to be as loving as possible, he is not so happy about how close Affleck and Garner — who were married from 2005-2018 — have become.

“Privately, he has been known to find it a little bit intimidating that she’s still so close to Ben,” the source said. "Especially when he’s reminded about their red-hot connection back in the day.”

“Her comment about the camera crew needing a wide lens for Ben’s naked shower scene in Gone Girl has come back to haunt Jen because it really bugs John to know that,” the insider spilled. “But he doesn’t dwell on it, he understands she had a past before him and that there is still a place for Ben in her life.”

While Miller may be having a hard time with their arrangement, he is not looking to drive Affleck away.

“He’s very clear he’s not looking to force Ben out of Jen’s life, but the 24/7 nature of their relationship is just becoming way too much,” they explained. “Whenever they’re together, Ben’s blowing her up with random questions. And now they’re doing this movie together, it’s really got him questioning where he stands.”

Affleck and Garner have recently started working on his upcoming flick, Animals, together. The last time the former lovebirds worked on a film they began dating.

“Jen has assured John and everyone else that she’s still all in, but you can’t blame the guy for wanting some actions to back up her words,” the source noted.

As OK! previously reported, Affleck’s need for Garner’s help came amid his split from Lopez, who filed for divorce on August 20.

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Life & Style reported on Garner, Miller and Affleck's relationship after his divorce from Lopez.