Ben Affleck & Jen Garner -- Dinner for Two ... Without the Kids

Jennifer Garner went on a romantic dinner date in Malibu -- with her estranged husband Ben Affleck, and for once this was NOT about family time.

Ben and Jen were seen leaving Nobu Sunday night in Malibu. While the maybe exes have been together semi-frequently since annoucing their divorce in June, it's usually because they're doing things with their 3 kids.

The Nobu date was strictly for adults. According to ET, they drove there together and left together ... but there was no PDA.

Baby steps?