J Lo's 48-year-old boyfriend sprang into action when 13-year-old Emme needed it most after things turned chaotic while they were shopping in The Hamptons.
Affleck escorted Emme and her friend to a bookstore on Tuesday while the Love Don't Cost a Thing singer stayed behind in the car riding shotgun.
It was clearly meant to be a quick in and out situation until the paparazzi caught wind of where the duo was located.
As Affleck exited the quaint bookstore with J Lo's daughter, a chaotic scene unfolded.
Paparazzi seemingly pushed through each other to get the shot, and the Oscar-winning actor switched into dad mode.
Affleck could be seen in his lightning bolt t-shirt, placing his hand on Emme's back as he guided her past shutterbugs.
Emme appeared to be taken back by all the attention.
Sporting her blue hair, green shirt, and flannel tee, she happily obliged when Affleck took the lead and got her to safety.
The Argo actor not only took care of Emme as J Lo lovingly looked on, but he made sure to keep her friend close too.
Affleck was also photographed telling the paparazzi to keep their distance from the girls as he opened their car door and let them slip inside.
He's been getting close with J Lo's kids over the past recent weeks.
Affleck was first spotted bonding with Emme and her twin brother, Max, during a family dinner at celebrity hotspot Nobu in Malibu.
The siblings didn't seem to mind when Affleck and J Lo shared a passionate kiss for dessert.
At the time, Radar exclusively reported that the couple dubbed "Bennifer" had yet to introduce their children.
Affleck has three kids of his own -- Violet, 15, Seraphina, 12, and Samuel, 9 -- who he shares with ex-wife Jen Garner.
That all changed ahead of the weekend when the duo was seen with their blended family at Universal Studios in Los Angeles.
One day later, Affleck and J Lo were seen taking a loving stroll in The Hamptons. They couldn't keep their hands off one another, despite the singer's ex Alex Rodriguez living only minutes away.
A-Rod didn't appear to see the couple. He was too busy mediating Meek Mill's fight with Travis Scott at Michael Rubin's star-studded Fourth of July party.