BG, I think you're right, but there are barriers to fully experiencing compersion too. You can both feel joy at your partners good fortune while being jealous that it's not with you. The trick is overcoming the latter so you're only left with the good feelings.
Me: 41 straight male in a V with
Wife: Kay - mono female - married 18 years
LDR ex? girlfriend: Susan - serial monogamist female - 4 year relationship ended? 9/29
Stakes - very intimate friend