Jennifer Garner is NOT getting back with her ex-husband Ben Affleck in the wake of his divorce … she’s happily in a relationship with her boyfriend John Miller, despite reports to the contrary.

Sources close to the situation tell TMZ … Jen and John are still very much together — despite a report they are on a break — and their relationship has NOT changed as a result of Jennifer Lopez filing to divorce Ben.

In the wake of Bennifer’s implosion, there are rumors Jen is also unhappy with her man … but we’re told that’s just not the case here.

Ben and Jen are co-parenting rockstars, though … and they just got done dropping their daughter Violet off at Yale this week, flying back to Hollywood in a private jet together.

In fact, Ben was all smiles hopping off the jet Wednesday … the day after J Lo filed for divorce after a months-long buildup. Seems Ben’s pretty chipper about life, despite the relationship turmoil.

JG and John, we’re told, are solid too … and that’s just one reason why Ben’s not about to reenter the picture … at least in the romantic sense.

Our sources also say John is well versed in Jen and Ben’s co-parenting situation … and he’s not bothered by their arrangement and is very confident in his relationship with Jennifer.

Women love a man with confidence, just sayin’.