Jennifer Lopez is letting us in on some very raunchy details about her marriage with Ben Affleck -- singing about their sex life in one of her new songs ... and yeah, it's raunchy.

Things get hot and heavy in the sultry new tune "Greatest Love Story Never Told" from her new album, "This Is Me… Now." Listen to these NSFW lyrics ... "Missing your body, Climbing on top of me, Slipping inside of me, Way that I ride it, Bodies aligning, Look at our timing."

Yeah, there's clearly no such thing as TMI when it comes to J Lo ... at least not these days.

The song isn't entirely X-rated though ... she also sings of how it was "destiny" they "found each other twice in one lifetime." Just another example that she and Ben are deeply in love.

Listeners were diggin' the emotionally charged tune ... some self-proclaimed hopeless romantics said they could totally relate to it, and that it was their favorite from her first album in a decade, which was trending heavily on X Friday.

While Ben obviously served as a major inspo on the new album, he also got involved personally -- lending some background vocals for "Not Going Anywhere." Yep, he's credited.

After their famous relationship ended in the early 2000s, J&B got back together in 2021, with plenty of cozy sightings, including some nostalgic yacht trips, of course -- and thankfully, the singer has made it clear they're much more secure now than they were previously.

So much so, in fact, that she made an album that heavily touches on their relationship.

One thing's for sure: she's into her hubby -- and, as we've learned, he's really into her too!

J Lo's killing it right now -- not only is her new album being well-received by fans, but this film of hers is being praised as well. There's a separate doc coming soon too ... "The Greatest Love Story Never Told," which is hitting Prime in due time.