"Jen and John have stayed friends.They're not super close at the moment but Jen has said she likes the John-Katy pairing a lot and wants to see them start a family together," a source close to the situation told Radar.
"Of course Jen is in such a good place with her own relationship that she can get away with being magnanimous."
Aniston, 44, has been dating Justin Theroux since 2011 and the pair announced their engagement on Aug. 12, 2012.
"But when she was single, she didn't want to hear a thing about John's hook-ups, and to his credit, he kept his personal life pretty low key for the two years after they broke up," the source added.
Mayer and Aniston began dating in Feb. 2008 and after a brief breakup got back together, only to break up for good in March 2009.
The source concluded, "No matter what happens, there's a lot of mutual respect between John and Jen that doesn't exist between Jen and Brad Pitt at the moment."
After a seven-year marriage, Aniston and Pitt filed for divorce in 2005 after speculation that he cheated on her with Angelina Jolie, who he later went on to have six children with.