Sanders was pictured wearing his wedding ring days after he was photographed kissing Stewart in a car. Both have issued apologies since then with Stewart calling it a "momentary indiscretion".
Pattinson, who started dating Stewart after meeting her on the set of 'Twilight' four years ago, is reportedly keen to have a heart-to-heart with Ross for the peace of his mind, the Daily Mirror reported quoting sources.
"He needs to know for his own peace of mind if theirs was just a fleeting moment. He hopes Liberty can help him find the answers to he so desperately craves," a source told the newspaper.
Liberty, 33, and Sanders,41, have been married for 10 years and have two daughters together.
She has remained silent on her husband's liaison with her 'Snow White and The Huntsmen' co-star.
Pattinson and Stewart will have to attend the promotional tour for the final film in the 'Twilight' saga which is releasing soon.
