Paging Maury: After months of cheating rumors, pregnant reality star Kourtney Kardashian challenged longtime boyfriend Disick to a moment of truth with a lie detector test!

The couple ended their 10-month engagement last February after the Keeping Up With The Kardashians personality became concerned that Scott was secretly seeing women behind her back. The two later reconciled and Kourtney became pregnant. But the 30-year-old L.A. socialite has had a tough time shaking suspicions that Scott is anything but a one-woman man. So Scott hired private investigator Kelly Duhs, of Moorpark, California, to administer a polygraph, Star Magazine reports in its Nov. 23 issue.

“Kourtney heard whispers about him cheating while he was partying in the Hamptons this summer, and she eventually threw him out,” an insider dished. “The only chance to save his relationship was to prove his innocence with a lie detector test,” the spy adds. “He was nervous, because he hadn’t taken one before.”

It turns out there was nothing to worry about. Scott passed the polygraph with flying colors and Kourt happily allowed him to move back in.

Scott and Kourtney’s baby boy is due next month.