Jennifer Lopez is back in her native city after her extended birthday Hamptons trip -- and while there's still no Ben Affleck in sight ... there is a remnant of him around.

The singer/actor popped up in NYC Thursday ... where she was galivanting around town in a stylish 'fit and looking pretty damn fabulous to boot. Per usual, she was rolling with her manager Benny Medina and a small entourage ... but J Lo was out there looking confident.

First, she went to lunch in SoHo ... where she was flashing a big smile, but more importantly -- her wedding ring, which she seems to have mostly been rocking of late.

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Later on that same evening ... she went to dinner at the Crosby Hotel in Lower Manhattan -- where she met up with her mama and some other friends. Again ... no Ben here, just like her entire stay in the Hamptons.

Jen's been rolling solo on the East Coast for about two weeks now -- this while her husband has remained in Cali amid what appears to be a rough patch in their marriage. From the outside looking in ... it certainly looks like they're headed for divorce.

They're in the middle of trying to sell their pad ... and Ben's been staying in a rental. In the meantime, J Lo's living out loud in the Big Apple -- without a care in the world, it seems.