Ben Affleck‘s close friend Jason Mewes ain’t buying into the swirling speculation the actor’s marriage to Jennifer Lopez is crumbling … not based on what he’s seen.

We got Jason out Wednesday in L.A., and he told us after witnessing Ben and Jen’s genuine affection at their wedding less than 2 years ago, he’d be downright shocked if the rumors were true.

Jason expresses some frustration over people immediately jumping to split speculation … suggesting there’s probably a more practical explanation — most likely work-related — behind Ben moving out of their marital home.

He theorizes Ben might crave some peace and quiet to focus while filming for his new movie, free from the chaos of family life — or hey, J Lo might not be too keen on Ben’s film collaborators coming and going at their home.

JM clarifies he’s just throwing out possibilities, emphasizing he hasn’t been in close contact with Ben since their 2022 wedding, so he’s not sure what’s really going on between them.

As we reported, Ben’s currently renting a place in Brentwood, while Jen remains in their lavish $60 million Beverly Hills mansion they bought together.

The situation’s been a bit of a rollercoaster, with Ben spotted sans wedding band one day, then sporting it again the next.

They then threw everyone for a loop by stepping out for a family outing Sunday … but in another twist, the very next day, J Lo hit the premiere for her new movie “Atlas” by herself.