Rupert Sanders & Liberty Ross -- HUGGIN' IT OUT

Rupert Sanders has proven ... you CAN bang a hot Hollywood actress behind your wife's back and still make it all good again ... and we have the pics to prove it.

Rupert and Liberty Ross shared a great big HUG after leaving a counseling session in Beverly Hills Wednesday. We broke the story ... just weeks after the Kristen Stewart cheating scandal broke, Liberty and Rupert were seeing the counselor.

We also told you ... Liberty went to see a divorce lawyer after the story broke but she has not pulled the trigger and wants to save the marriage.

Our sources say Liberty has laid down some ground rules for any reconciliation ... which includes an extramarital banging ban.

Judging by the hug, it seems they're making some serious progress ... but neither Rupert nor Liberty was wearing a wedding ring at the time of the embrace. They arrived and left separately.

Seems to be the season for forgiveness ... just a few days ago, Robert Pattinson was photographed hangin' out with Kristen.