The actor sat down as a guest for Kevin Hart's most recent episode of his 'Hart to Heart' talk show -- and yes, they got into Ben and Jen's marriage ... in fact, Ben talked about it at length, and he had some interesting insights.

For starters, he called J Lo his "wife" in this sit-down ... while at the same time pointing out that she draws a ton of attention, something he notes he's not really a huge fan of.

Check out Ben's characterization of this for yourself ... he says it's "bananas" how famous Jen is -- explaining that when they go out, people are falling over themselves over her ... whereas they don't really freak out over seeing him.

Something else Ben made perfectly clear in this interview ... he does NOT like attention and cameras in his face -- especially when his kids are around -- and that's undoubtedly increased by a lot since he's gotten back with J Lo.

It's a fascinating convo -- but what's even more interesting is the fact that Ben is bearded here ... and the reason that's noteworthy is because he's not rockin' a beard these days, so this interview is actually pretty old.

Ben was wearing a beard in late February ... but come mid-to-late March, he'd ditched it completely for a new movie he's shooting -- so that means his comments in the KH show are likely from February or possibly even before.

One last thing of note ... Ben says he feels he has 5 kids now instead of 3 -- suggesting Jen's two children are part of his family, and he doesn't distinguish them at all.