Indeed, jealousy stinks. I should know, I'm the jealous one around here. I don't know where it comes from, I've read all the theory and it doesn't quite jibe. I think it has a little to do with an overactive imagination, personally.

No matter the reason, what works (at least some), is meeting and getting to know the person/people you're jealous of. It's a lot easier to be jealous of a nameless and in your mind amazingly athletic and charming and cute and flirtatious person that your SO is having a ball with, than being jealous of ol' Brad with the paunch and wife and 3 kids who isn't really that funny but a good sport to ride with. And observing how your SO isn't falling over herself to make an impression on Brad, but simply out there to ride with a riding buddy.

Body language does tell you a lot more than words, and observing how two people act together will set your mind at rest a lot more than anybody telling you how innocent it all is.

Did that make sense?