J Lo and Ben Affleck Do Sunday Funday Together Despite Living Apart

Jennifer Lopez and Ben Affleck seem to be saying they're all good, maritally speaking -- even though they're not living under the same roof, they spent much of Sunday together ... looking like a happy couple.

The apparently estranged couple met up Sunday in Santa Monica, where they both showed out to support J Lo's kid, Emme, in a school event. Jennifer Garner also showed up with Fin, as Ben and Jen's kid is pretty tight with Emme.

Anyway, things got more interesting when they left Santa Monica -- Ben was smiling behind the wheel, and Jennifer was in his passenger seat, as they headed out ... apparently to grab dinner together at BOA Steakhouse in WeHo.

Of course, they were photographed as they left dinner, too ... which is not shocking. BOA is one of the L.A. restaurants where all celebs know the paps are gonna take their photo.

If Jen and Ben really wanted alone time, they could've stayed at BOA in Santa Monica -- same menu, but way less attention.

As we've reported ... Ben has been living in Brentwood in a home he's renting, while Jennifer continues living in the $60 million Bev Hills mansion they bought together.

We also told you that Ben did not wear his wedding ring during a Friday outing, but he had it back on come Saturday outside his rental home.