Kevin Hart's clearly got a cheating problem and needs help to turn it around ... so says "Couples Therapy" star Dr. Jenn Mann.

We got the doc out in Bev Hills Thursday and had a couch session with her that was totally raw and uncut. She's not pulling punches here, so Kevin might not wanna listen.

Once a cheater, always a cheater? Do celebrities get a pass? Does having a kid on the way make things more complicated? Jenn tackles it all, and says there IS hope for Kevin.

The doctor is in.