No one said co-parenting after divorce was easy! Ben Affleck and Jennifer Garner are just like the rest of us ... trying to figure out how to keep their romantic and personal lives separate from their parenting duties and it doesn't always go well.

Ben and Jen appeared to have a blowout fight at son Samuel's basketball game on Saturday at a local gym. Ben certainly looked pissed and Jennifer appeared to be ... well ... conciliatory. Someone's gotta be the bigger person!

Meanwhile, poor little Samuel licked his ice cream cone and seemed to have the hardened coping techniques of a child of divorce -- to keep calm and carry on and pretend like mommy and dating aren't fighting ... again. Awww!