I think MJD hit on something really big there... I'd be a lot more threatened if I felt like the other guy was getting something that I wasn't getting, even moreso if I felt it was being kept from me.
It wouldn't matter so much what The Thing was. What would matter is how it made me feel. Speaking in generalities, if I am feeling any lacking in the connection to my partner and then I see something that seems symbolic of that connection with another guy, I'd become jealous.
So it seems that the cure for the situation isn't so much a modification of a single behavior, as some soul searching about what exactly is being threatened and how that can be reassured in a healthy way.