Your significant other's a flirt; you're more of the quiet type. And, well, you're jealous for two reasons: 1. He or she's paying attention to someone else; and 2. You wish you were so outgoing. Don't create a scene, in fact, don't even bring it up. Let your sweetie get it out of their system; besides, it's harmless. Now, go ahead and strike up a conversation with someone else: you'll feel liberated.