Jennifer Garner has been quietly dating John Miller since 2018. They’re seen out together somewhat regularly, but he’s never walked a red carpet with her and, obviously, they’ve spent years never putting their relationship on display. I’ve never really paid much attention to him, and as I was looking through photos of him, he definitely reminded me of Michael Vartan (who J-Garner dated many lifetimes ago). By all accounts, Miller is a solid, low-drama guy who respects that his partner successfully co-parents with her ex-husband. Unfortunately, Garner’s ex-husband is a giant drama queen who uses Garner to get back at his other ex-wife. Ben Affleck made a big show of affection with Garner at their son Samuel’s birthday party, then Ben wouldn’t shut up about how he wants another shot with Garner. Garner made it clear that she’s not interested, then sources close to Ben ranted about how he wants nothing to do with Jennifer Lopez. A lot has happened in the past few weeks, and all of it has been very stupid. So how does John Miller feel about it?

Jennifer Garner’s boyfriend, John Miller, issued an ultimatum after Ben Affleck was spotted getting cozy with his ex-wife, a source exclusively tells Page Six. The CaliBurger CEO “has always been supportive of Ben and Jen’s co-parenting relationship but feels Ben crossed the line,” the insider says.

“John knows there’s nothing going on between Jen and Ben, but he doesn’t think those photos are a good look and feels it’s disrespectful to their relationship.”

According to the source, Miller, 47, “gave Jen an ultimatum” — “he doesn’t want to see anything like that again or he has no choice but to walk away.”

The “Gone Girl” star, 52, was seen affectionately grabbing the “13 Going on 30” actress, also 52, as the couple celebrated their son Samuel’s 13th birthday on March 2. The Oscar winner grabbed the Emmy nominee around the waist as she focused her paintball gun on a target at the Combat Paintball Park in Castaic, Calif. Affleck pulled Garner in toward him, and she appeared to welcome the embrace. The “Daredevil” co-stars — who also share Violet, 19, and Seraphina, 16 — looked cozy as they laughed and closely chatted while participating in the festivities.

Reps for Miller, Garner and Affleck did not immediately respond to Page Six’s requests for comment.

As Page Six previously reported, Miller hasn’t been “thrilled” about the exes — who were married from 2005 to 2018 — spending more time together. Miller “knows Ben and Jen have been leaning on each other more than ever lately and have a really close relationship.”

“Their growing bond is getting to be a bit much when Ben spends all the holidays with them like Christmas and Thanksgiving,” the insider said. “John feels like a third wheel.”

[From Page Six]

Here’s the thing… while this is Page Six and should be treated with suspicion, I actually think Ben’s behavior has been inappropriate and disrespectful, and I could totally see how Garner’s partner would feel the same. Now, is Miller issuing ultimatums or whatever? I have no idea, but I can’t imagine that Miller is pleased with Ben’s antics these days. That being said, Garner has made it perfectly clear that she has no interest in Ben’s attempt at reconciliation, or whatever this was. I think Ben is trying to cause problems for BOTH Jennifers – and I hope both Jennifers ignore him.

Photos courtesy of YouTube screenshots and Backgrid.