Jennifer Lopez and Ben Affleck aren't even doing the air kiss thing anymore ... they were both at his son's graduation ceremony, but kept their distance and separated their families.

The couple arrived and exited separately Wednesday at a grad ceremony for Ben's 12-year-old son Samuel, who he shares with ex-wife Jennifer Garner.

Ben showed up to the milestone family occasion with his mom, while J Lo pulled up with her twins, Emme and Max, in tow. The man of the hour here is Ben's son, but J Lo got there first before Papa Bear.

With their marriage seemingly on the outs, Ben and Jen appeared to steer clear of one another at the graduation ... another tell-tale sign of the state of their union. Like we said, not even the slightest air kiss.

TMZ broke the story ... the couple is clearly hurtling towards divorce because Ben's moved out to a rental home in Brentwood, and they are quietly trying to sell the family home in Bev Hills that they bought after getting hitched.

Still, Ben's wearing his wedding ring here ... unclear if J Lo did the same, her hand is hidden in the photos. Jen did, however, wear her wedding ring over the weekend to dinner.

We've seen Ben and Jen put on a united front at a graduation event last month for Ben's daughter Violet. The difference at Wednesday's gathering is they're no longer attempting to even appear copacetic.