This video (sorry for the facebook link) is of a "Couples Swap Phones" experiment. The girl finds next to nothing on her boyfriends phone. But he goes into her instagram DMs and finds a plethora of orbiters being kept on the back burner. She provides little to no coherent explanation "we have mutual friends!", "I don't know him", etc... for each of the interactions. But it becomes clear she is being flirtatious, giving out her number, her snapchat, and just generally leading them on. She says that she's denied all of them, but the messages themselves reveal a different story (re: pay attention to what she does, not what she says). She's likely doing this for the validation, or to have backup men ready in case her current relationship falls through.
Remember this: Every woman will at least attempt to keep a circle of orbiters around, no matter how much she "loves you" in an LTR. The more attractive she is, the easier this will be, and the advent of social media is making this even easier. Your relationship is never safe, always remember to keep improving yourself, be a leader, and have a steady stream of dread trickling in.