Heidi & Spencer REJECT 'Relationship Rehab' -- It's Not You, It's Us

12/18/2011 5:00 AM PST

Heidi Montag & Spencer Pratt Reject 'Relationship Rehab' -- It's Not You, It's Us

Now this is painful -- TMZ has learned, "Relationship Rehab" producers approached Heidi Montag and Spencer Pratt to work out their issues on the show ... and the couple flat-out rejected their offer.

Speidi's reasoning -- they're actually on great terms ... and don't have any issues to work out.

Sources close to Speidi tell us, the couple was initially intrigued -- thinking the show was actually about working out together ... as in yoga, or something like it. They had no idea it was for couples with real issues.

We're told the couple felt the money wasn't great either, so they passed on the show. Spencer and Heidi turning down a chance at spotlight ... we're speechless.